Movable body drive method and movable body drive system, and pattern formation method and pattern formation apparatus

ABSTRACT

A first positional information of a wafer stage is measured using an interferometer system such as, for example, a Z interferometer. At the same time, a second positional information of the wafer stage is measured using a surface position measurement system such as, for example, two Z heads. Moving average is applied to a difference between the first positional information and the second positional information for a predetermined measurement time to set a coordinate offset, which is used to inspect the reliability of output signals of the surface position measurement system. When the output signals are confirmed to be normal, servo control of the wafer stage is performed using a sum of the first positional information and the coordinate offset. According to this hybrid method, drive control of the wafer stage which has the stability of the interferometer and the precision of the Z heads becomes possible.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Division of U.S. patent application Ser. No. 12/230,068 filedAug. 22, 2008 (now U.S. Pat. No. 8,085,385), which in turn is anon-provisional application that claims the benefit of U.S. ProvisionalApplication No. 60/960,157 filed Sep. 18, 2007. The disclosure of eachof the previous applications is hereby incorporated herein by referencein its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to movable body drive methods and movablebody drive systems, and pattern formation methods and pattern formationapparatuses, and more particularly, to a movable body drive method and amovable body drive system that drives a movable body substantially alonga two-dimensional plane, and a pattern formation method using themovable body drive method and a pattern formation apparatus equippedwith the movable body drive system.

2. Description of the Background Art

Conventionally, in a lithography process for manufacturing electrondevices (microdevices) such as semiconductor devices (such as integratedcircuits) and liquid crystal display devices, exposure apparatuses suchas a projection exposure apparatus by a step-and-repeat method (aso-called stepper) and a projection exposure apparatus by astep-and-scan method (a so-called scanning stepper (which is also calleda scanner) are mainly used.

However, the surface of a wafer serving as a substrate subject toexposure is not always flat, for example, by undulation and the like ofthe wafer. Therefore, especially in a scanning exposure apparatus suchas a scanner and the like, when a reticle pattern is transferred onto ashot area on a wafer by a scanning exposure method, positionalinformation (surface position information) related to an optical axisdirection of a projection optical system of the wafer surface isdetected at a plurality of detection points set in an exposure area, forexample, using a multiple point focal point position detection system(hereinafter also referred to as a “multipoint AF system”) and the like,and based on the detection results, a so-called focus leveling controlis performed (refer to, for example, Kokai (Japanese Patent UnexaminedApplication Publication) No. 6-283403) to control the position in theoptical axis direction and the inclination of a table or a stage holdinga wafer so that the wafer surface constantly coincides with an imageplane (within the focal depth of the image plane) of the projectionoptical system in the exposure area.

Further, with the stepper or the scanner and the like, wavelength ofexposure light used with finer integrated circuits is becoming shorteryear by year, and numerical aperture of the projection optical system isalso gradually increasing (larger NA), which improves the resolution.Meanwhile, due to shorter wavelength of the exposure light and larger NAin the projection optical system, the depth of focus had becomeextremely small, which caused a risk of focus margin shortage during theexposure operation. Therefore, as a method of substantially shorteningthe exposure wavelength while substantially increasing (widening) thedepth of focus when compared with the depth of focus in the air, theexposure apparatus that uses the liquid immersion method has recentlybegun to gather attention (refer to, for example, the pamphlet ofInternational Publication No. 2004/053955).

However, in the exposure apparatus using this liquid immersion method orother exposure apparatus whose distance (working distance) between thelower end surface of the projection optical system and the wafer issmall, it is difficult to place the multipoint AF system in the vicinityof the projection optical system. Meanwhile, in the exposure apparatus,in order to realize exposure with high precision, realizing surfaceposition control of the wafer with high precision is required.

Further, with the stepper or the scanner or the like, positionmeasurement of the stage (the table) which holds a substrate (forexample, a wafer) subject to exposure is performed in general, using alaser interferometer having a high resolution. However, the optical pathlength of the laser interferometry beam which measures the position ofthe stage is around several hundred mm or more, and furthermore, due tofiner patterns owing to higher integration of semiconductor devices,position control of the stage with higher precision is becomingrequired. Therefore, short-term variation of measurement values which iscaused by air fluctuation which occurs due to the influence oftemperature fluctuation or temperature gradient of the atmosphere on thebeam optical path of the laser interferometer can no longer be ignored.

Accordingly, in the case of performing position control of the table inan optical axis direction and in a tilt direction with respect to theplane orthogonal to the optical axis, including focus leveling controlof the wafer during exposure, based on measurement values of theinterferometer, it is desirable to correct measurement errors caused byair fluctuation and the like of the interferometer by some sort ofmethod.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda movable body drive method in which a movable body is drivensubstantially along a two-dimensional plane, the method comprising: adrive process in which positional information of the movable bodyrelated to at least one of a direction orthogonal to the two-dimensionalplane and a tilt direction with respect to the two-dimensional plane isdetected, using a first detection device which detects positionalinformation of the movable body in a direction orthogonal to thetwo-dimensional plane from measurement results using measurement lightirradiated along the two-dimensional plane between the outside of anoperating area of the movable body and the movable body, and a seconddetection device that has at least one detection position placed in atleast a part of an operating area of the movable body, and detectspositional information of the movable body in a direction orthogonal tothe two-dimensional plane using detection information detected when themovable body is positioned at the detection point, and the movable bodyis driven based on positional information detected by the firstdetection device in at least one of a direction orthogonal to thetwo-dimensional plane and a tilt direction with respect to thetwo-dimensional plane, and the movable body is also driven so thatpositional information detected by the first detection device when themovable body is positioned at the detection position of the seconddetection device is adjusted, using positional information detected bythe second detection device.

According to this method, the movable body can be driven with goodprecision in at least one of a direction orthogonal to thetwo-dimensional plane and a tilt direction with respect to thetwo-dimensional plane, based on the positional information detected bythe first detection device whose error component has been corrected,while correcting error components of the positional information detectedby the first detection device caused by air fluctuation of a measurementbeam irradiated along the two-dimensional plane between the outside ofthe operating area of the movable body and the movable body.

According to a second aspect of the present invention, there is provideda first pattern formation method to form a pattern on an object whereina movable body on which the object is mounted is driven using themovable body drive method according to the present invention to performpattern formation to the object.

According to this method, by forming a pattern on the object mounted onthe movable body which is driven with good precision using the firstmovable body drive method of the present invention, it becomes possibleto form a pattern on the object with good accuracy.

According to a third aspect of the present invention, there is provideda second pattern formation method in which a pattern is formed on anobject held by a movable body moving substantially along atwo-dimensional plane, the method comprising: a drive process in whichwhile positional information of the movable body in a directionorthogonal to the two-dimensional plane and a tilt direction withrespect to the two-dimensional plane is detected, using a firstdetection device that detects positional information of the movable bodyrelated to a direction orthogonal to the two-dimensional plane and atilt direction with respect to the two-dimensional plane frommeasurement results using a measurement beam irradiated along thetwo-dimensional plane between the outside of the operating area of themovable body and the movable body, and a second detection device thathas a plurality of detection positions and detects positionalinformation of the movable body related to a direction orthogonal to thetwo-dimensional plane at each detection position, the movable body isdriven in at least one of a direction orthogonal to the two-dimensionalplane and a tilt direction with respect to the two-dimensional planebased on the information detected by the first detection device; and acalibration process in which a predetermined calibration processing isperformed using the detection information of the second detection deviceto improve alignment precision of a pattern with the object in at leastone of a direction orthogonal to the two-dimensional plane and a tiltdirection with respect to the two-dimensional plane.

According to this method, the movable body is driven in a directionorthogonal to the two-dimensional plane and a tilt direction withrespect to the two-dimensional plane, based on the information detectedby the first detection device which is superior in long-term stabilityof the measurement by the measurement principle, and a predeterminedcalibration processing is performed in order to improve alignmentaccuracy of the pattern and the object in a direction orthogonal to thetwo-dimensional plane and the tilt direction with respect to thetwo-dimensional plane, using information detected by the seconddetection device whose short-term stability of measurement is superior(measurement with high precision is possible) when compared with thefirst detection device. As a consequence, it becomes possible to form apattern on an object held by the movable body with high accuracy, forover a long period of time.

According to a fourth aspect of the present invention, there is provideda movable body drive system in which a movable body is driven along asubstantially two-dimensional plane, the system comprising: a firstdetection device that detects positional information of the movable bodyin a direction orthogonal to the two-dimensional plane from measurementresults using a measurement beam irradiated along the two-dimensionalplane between the outside of the operating area of the movable body andthe movable body; a second detection device that has at least onedetection position placed in at least a part of an operating area of themovable body, and detects positional information of the movable body ina direction orthogonal to the two-dimensional plane using detectioninformation detected when the movable body is positioned at thedetection point; and a controller that detects positional information ofthe movable body in at least one of a direction orthogonal to thetwo-dimensional plane and a tilt direction with respect to thetwo-dimensional plane using the first detection device and the seconddetection device, and drives the movable body in at least one of adirection orthogonal to the two-dimensional plane and a tilt directionwith respect to the two-dimensional plane based on positionalinformation detected by the first detection device, while adjusting thepositional information of the movable body detected by the firstdetection device using the positional information detected by the seconddetection device.

According to this method, the movable body can be driven with goodprecision in at least one of a direction orthogonal to thetwo-dimensional plane and a tilt direction with respect to thetwo-dimensional plane, based on the positional information detected bythe first detection device whose error component has been corrected,while correcting error components of the positional information detectedby the first detection device caused by air fluctuation of a measurementbeam irradiated along the two-dimensional plane between the outside ofthe operating area of the movable body and the movable body.

According to a fifth aspect of the present invention, there is provideda first pattern formation apparatus that forms a pattern on an object,the apparatus comprising: a patterning device which generates a patternon the object; and the movable body drive system according to thepresent invention, wherein drive of a movable body on which the objectis mounted is performed by the movable body drive system for patternformation with respect to the object.

According to this apparatus, by generating a pattern with a patterningdevice on the object on the movable body driven with good precision bythe movable body drive system of the present invention, it becomespossible to form a pattern on the object with good precision.

According to a sixth aspect of the present invention, there is provideda second pattern formation apparatus in which a pattern is formed on anobject held by a movable body moving substantially along atwo-dimensional plane, the apparatus comprising: a first detectiondevice that detects positional information of the movable body relatedto a direction orthogonal to the two-dimensional plane and a tiltdirection with respect to the two-dimensional plane from measurementresults using a measurement beam irradiated along the two-dimensionalplane between the outside of the operating area of the movable body andthe movable body; a second detection device that has a plurality ofdetection positions, and detects positional information of the movablebody related to a direction orthogonal to the two-dimensional plane ateach detection position; and a controller which drives the movable bodyin at least one of a direction orthogonal to the two-dimensional planeand a tilt direction with respect to the two-dimensional plane based oninformation detected by the first detection device, while detectingpositional information of the movable body in a direction orthogonal tothe two-dimensional plane and a tilt direction with respect to thetwo-dimensional plane, using the first detection device and the seconddetection device, as well as performs a predetermined calibrationprocessing using the detection information of the second detectiondevice to improve alignment precision of a pattern with the object in atleast one of a direction orthogonal to the two-dimensional plane and atilt direction with respect to the two-dimensional plane.

According to this apparatus, the controller drives the movable body in adirection orthogonal to the two-dimensional plane and a tilt directionwith respect to the two-dimensional plane, based on the informationdetected by the first detection device which is superior in long-termstability of the measurement by the measurement principle, and performsa predetermined calibration processing in order to improve alignmentaccuracy of the pattern and the object in a direction orthogonal to thetwo-dimensional plane and the tilt direction with respect to thetwo-dimensional plane, using information detected by the seconddetection device whose short-term stability of measurement is superior(measurement with high precision is possible) when compared with thefirst detection device. As a consequence, it becomes possible to form apattern on an object held by the movable body with high accuracy, forover a long period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a view that schematically shows a configuration of an exposureapparatus of an embodiment;

FIG. 2 is a planar view showing a stage device in FIG. 1;

FIG. 3 is a planar view showing placement of various measurement devices(an encoder, alignment system, multipoint AF system, a Z head) whichexposure apparatus of FIG. 1 comprises;

FIG. 4A is a planar view showing a wafer stage, and FIG. 4B is aschematic side view of a partially sectioned wafer stage WST;

FIG. 5A is a planar view that shows a measurement stage MST, and FIG. 5Bis a partially sectioned schematic side view that shows measurementstage MST;

FIG. 6 is a block diagram showing a configuration of a control system ofthe exposure apparatus related to an embodiment;

FIG. 7 is a view schematically showing an example of a configuration ofa Z head;

FIG. 8A is a view showing an example of a focus sensor, FIGS. 8B and 8Care views used to explain the shape and function of a cylindrical lensin FIG. 8A;

FIG. 9A is a view showing a divided state of a detection area of atetrameric light receiving element, FIGS. 9B, 9C, and 9D are viewsrespectively showing a cross-sectional shape of reflected beam LB2 on adetection surface in a front-focused, an ideal focus, and a back-focusedstate;

FIGS. 10A to 10C are views used to explain focus mapping performed inthe exposure apparatus related to an embodiment;

FIGS. 11A and 11B are views used to explain focus calibration performedin the exposure apparatus related to an embodiment;

FIGS. 12A and 12B are views used to explain offset correction among AFsensors performed in the exposure apparatus related to an embodiment;

FIG. 13 is a view showing a state of the wafer stage and the measurementstage where exposure to a wafer on the wafer stage is performed by astep-and-scan method;

FIG. 14 is a view showing a state of both stages at the time ofunloading of the wafer (when the measurement stage reaches the positionwhere Sec-BCHK (interval) is performed);

FIG. 15 is a view showing a state of both stages at the time of loadingof the wafer;

FIG. 16 is a view showing the state of both stages in the (when a waferstage moved to the position which processed of the first half ofPri-BCHK) at switching time from stage servo control by theinterferometer to stage servo control by the encoder;

FIG. 17 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in three first alignment shot areasare being simultaneously detected using alignment systems AL1, AL2 ₂ andAL2 ₃;

FIG. 18 is a view showing a state of the wafer stage and the measurementstage when the former processing of focus calibration is performed;

FIG. 19 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in five second alignment shot areasare being simultaneously detected using alignment systems AL1 and AL2 ₁to AL2 ₄;

FIG. 20 is a view showing a state of the wafer stage and the measurementstage when at least one of the latter processing of Pri-BCHK and thelatter processing of focus calibration is being performed;

FIG. 21 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in five third alignment shot areasare being simultaneously detected using alignment systems AL1 and AL2 ₁to AL2 ₄;

FIG. 22 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in three fourth alignment shot areasare being simultaneously detected using alignment systems AL1, AL2 ₂ andAL2 _(a);

FIG. 23 is a view showing a state of the wafer stage and the measurementstage when the focus mapping has ended;

FIGS. 24A and 24B are views for explaining a computation method of the Zposition and the amount of tilt of the wafer stage using the measurementresults of the Z heads;

FIG. 25 is a view conceptually showing position control of the waferstage, uptake of a measurement value of the Z head, and the switchingtiming of the Z head;

FIGS. 26A to 26H are views to explain a handling procedure at the timeof temporary abnormality output of the Z head, using the two states,which are scale servo and focus servo;

FIG. 27 is a view showing an outline of a linkage process in a switchingto servo drive control of the wafer stage from the surface positionmeasurement system to the interferometer system, and the interferometersystem to the surface position measurement system;

FIG. 28 is a view showing an outline of a linkage process in a servodrive control of the wafer stage in a hybrid method in which theinterferometer system is used as the main system and the surfaceposition measurement system is used as a sub sensor system; and

FIG. 29 is a block diagram showing an outline of a synchronized drivecontrol of the reticle stage and the wafer stage of the hybrid method inwhich the surface position measurement system is used together with theinterferometer system.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described,referring to FIGS. 1 to 29.

FIG. 1 shows a schematic configuration of an exposure apparatus 100 inthe embodiment. Exposure apparatus 100 is a projection exposureapparatus of the step-and-scan method, namely the so-called scanner. Asit will be described later, a projection optical system PL is arrangedin the embodiment, and in the description below, a direction parallel toan optical axis AX of projection optical system PL will be described asthe Z-axis direction, a direction within a plane orthogonal to theZ-axis direction in which a reticle and a wafer are relatively scannedwill be described as the Y-axis direction, a direction orthogonal to theZ-axis and the Y-axis will be described as the X-axis direction, androtational (inclination) directions around the X-axis, the Y-axis, andthe Z-axis will be described as θx, θy, and θz directions, respectively.

Exposure apparatus 100 is equipped with an illumination system 10, areticle stage RST that holds a reticle R that is illuminated by anillumination light for exposure (hereinafter, referred to asillumination light, or exposure light) IL from illumination system 10, aprojection unit PU that includes projection optical system PL thatprojects illumination light IL emitted from reticle R on a wafer W, astage device 50 that has a wafer stage WST and a measurement stage MST,their control system, and the like. On wafer stage WST, wafer W ismounted.

Illumination system 10 includes a light source, an illuminanceuniformity optical system, which includes an optical integrator and thelike, and an illumination optical system that has a reticle blind andthe like (none of which are shown), as is disclosed in, for example,Kokai (Japanese Patent Unexamined Application Publication) No.2001-313250 (the corresponding U.S. Patent Application Publication No.2003/0025890) and the like. Illumination system 10 illuminates aslit-shaped illumination area IAR which is set on reticle R with areticle blind (a masking system) by illumination light (exposure light)IL with a substantially uniform illuminance. In this case, asillumination light IL, for example, an ArF excimer laser beam(wavelength 193 nm) is used. Further, as the optical integrator, forexample, a fly-eye lens, a rod integrator (an internal reflection typeintegrator), a diffractive optical element or the like can be used.

On reticle stage RST, reticle R on which a circuit pattern or the likeis formed on its pattern surface (the lower surface in FIG. 1) is fixed,for example, by vacuum chucking. Reticle stage RST is finely drivable ormovable in within an XY plane by a reticle stage drive system 11 (notshown in FIG. 1, refer to FIG. 6) that includes a linear motor or thelike, and reticle stage RST is also drivable in a scanning direction (inthis case, the Y-axis direction, which is the lateral direction of thepage surface in FIG. 1) at a designated scanning speed.

The positional information (including position (rotation) information inthe θz direction) of reticle stage RST in the XY plane (movement plane)is constantly detected, for example, at a resolution of around 0.25 nmby a reticle laser interferometer (hereinafter referred to as a “reticleinterferometer”) 116, via a movable mirror 15 (the mirrors actuallyarranged are a Y movable mirror (or a retro reflector) that has areflection surface which is orthogonal to the Y-axis direction and an Xmovable mirror that has a reflection surface orthogonal to the X-axisdirection). The measurement values of reticle interferometer 116 aresent to a main controller 20 (not shown in FIG. 1, refer to FIG. 6).Main controller 20 computes the position of reticle stage RST in theX-axis direction, Y-axis direction, and the θz direction based on themeasurement values of reticle interferometer 116, and also controls theposition (and velocity) of reticle stage RST by controlling reticlestage drive system 11 based on the computation results. Incidentally,instead of movable mirror 15, the edge surface of reticle stage RST canbe mirror polished so as to form a reflection surface (corresponding tothe reflection surface of movable mirror 15). Further, reticleinterferometer 116 can measure positional information of reticle stageRST related to at least one of the Z-axis, θx, and θy directions.

Projection unit PU is placed below reticle stage RST in FIG. 1.Projection unit PU includes a barrel 40, and projection optical systemPL that has a plurality of optical elements which are held in apredetermined positional relation inside barrel 40. As projectionoptical system PL, for example, a dioptric system is used, consisting ofa plurality of lenses (lens elements) that is disposed along an opticalaxis AX, which is parallel to the Z-axis direction. Projection opticalsystem PL is, for example, a both-side telecentric dioptric system thathas a predetermined projection magnification (such as one-quarter,one-fifth, or one-eighth times). Therefore, when illumination light ILfrom illumination system 10 illuminates illumination area IAR, a reducedimage of the circuit pattern (a reduced image of a part of the circuitpattern) of reticle R within illumination area IAR is formed, withillumination light IL that has passed through reticle R which is placedso that its pattern surface substantially coincides with a first plane(an object plane) of projection optical system PL, in an area IA (alsoreferred to as an exposure area) conjugate to illumination area IAR onwafer W whose surface is coated with a resist (a sensitive agent) and isplaced on a second plane (an image plane) side, via projection opticalsystem PL (projection unit PU). And by reticle stage RST and wafer stageWST being synchronously driven, the reticle is relatively moved in thescanning direction (the Y-axis direction) with respect to illuminationarea IAR (illumination light IL) while wafer W is relatively moved inthe scanning direction (the Y-axis direction) with respect to exposurearea IA (illumination light IL), thus scanning exposure of a shot area(divided area) on wafer W is performed, and the pattern of the reticleis transferred onto the shot area. That is, in the embodiment, thepattern is generated on wafer W according to illumination system 10, thereticle, and projection optical system PL, and then by the exposure ofthe sensitive layer (resist layer) on wafer W with illumination lightIL, the pattern is formed on wafer W.

Incidentally, although it is not shown, projection unit PU is installedin a barrel platform supported by three struts via a vibration isolationmechanism. However, as well as such a structure, as is disclosed in, forexample, the pamphlet of International Publication WO2006/038952 and thelike, projection unit PU can be supported by suspension with respect toa mainframe member (not shown) placed above projection unit PU or withrespect to a base member on which reticle stage RST is placed.

Incidentally, in exposure apparatus 100 of the embodiment, becauseexposure is performed applying a liquid immersion method, an opening onthe reticle side becomes larger with the substantial increase of thenumerical aperture NA of projection optical system PL. Therefore, inorder to satisfy Petzval's condition and to avoid an increase in size ofthe projection optical system, a reflection/refraction system (acatodioptric system) which is configured including a mirror and a lenscan be employed as a projection optical system. Further, in wafer W, inaddition to a sensitive layer (a resist layer), for example, aprotection film (a topcoat film) or the like which protects the wafer ora photosensitive layer can also be formed.

Further, in exposure apparatus 100 of the embodiment, in order toperform exposure applying the liquid immersion method, a nozzle unit 32that constitutes part of a local liquid immersion device 8 is arrangedso as to enclose the periphery of the lower end portion of barrel 40that holds an optical element that is closest to an image plane side(wafer W side) that constitutes projection optical system PL, which is alens (hereinafter, also referred to a “tip lens”) 191 in this case. Inthe embodiment, as shown in FIG. 1, the lower end surface of nozzle unit32 is set to be substantially flush with the lower end surface of tiplens 191. Further, nozzle unit 32 is equipped with a supply opening anda recovery opening of liquid Lq, a lower surface to which wafer W isplaced facing and at which the recovery opening is arranged, and asupply flow channel and a recovery flow channel that are connected to aliquid supply pipe 31A and a liquid recovery pipe 31B respectively.Liquid supply pipe 31A and liquid recovery pipe 31B are slanted byaround 45 degrees relative to the X-axis direction and the Y-axisdirection in a planar view (when viewed from above) as shown in FIG. 3,and are placed symmetric to a straight line (a reference axis) LV whichpasses through the center (optical axis AX of projection optical systemPL, coinciding also with the center of exposure area IA previouslydescribed in the embodiment) of projection unit PU and is also parallelto the Y-axis.

One end of a supply pipe (not shown) is connected to liquid supply pipe31A while the other end of the supply pipe is connected to a liquidsupply device 5 (not shown in FIG. 1, refer to FIG. 6), and one end of arecovery pipe (not shown) is connected to liquid recovery pipe 31B whilethe other end of the recovery pipe is connected to a liquid recoverydevice 6 (not shown in FIG. 1, refer to FIG. 6).

Liquid supply device 5 includes a liquid tank for supplying liquid, acompression pump, a temperature controller, a valve for controllingsupply/stop of the liquid to liquid supply pipe 31A, and the like. Asthe valve, for example, a flow rate control valve is preferably used sothat not only the supply/stop of the liquid but also the adjustment offlow rate can be performed. The temperature controller adjusts thetemperature of the liquid within the tank, for example, to nearly thesame temperature as the temperature within the chamber (not shown) wherethe exposure apparatus is housed. Incidentally, the tank, thecompression pump, the temperature controller, the valve, and the like donot all have to be equipped in exposure apparatus 100, and at least partof them can also be substituted by the equipment available in the plantor the like where exposure apparatus 100 is installed.

Liquid recovery device 6 includes a liquid tank for collecting liquid, asuction pump, a valve for controlling recovery/stop of the liquid vialiquid recovery pipe 31B, and the like. As the valve, it is desirable touse a flow control valve similar to the valve of liquid supply device 5.Incidentally, the tank, the suction pump, the valve, and the like do notall have to be equipped in exposure apparatus 100, and at least part ofthem can also be substituted by the equipment available in the plant orthe like where exposure apparatus 100 is installed.

In the embodiment, as liquid Lq described above, pure water(hereinafter, it will simply be referred to as “water” besides the casewhen specifying is necessary) that transmits the ArF excimer laser light(light with a wavelength of 193 nm) is to be used. Pure water can beobtained in large quantities at a semiconductor manufacturing plant orthe like without difficulty, and it also has an advantage of having noadverse effect on the photoresist on the wafer, the optical lenses orthe like.

Refractive index n of the water with respect to the ArF excimer laserlight is around 1.44. In the water the wavelength of illumination lightIL is 193 nm×1/n, shortened to around 134 nm.

Liquid supply device 5 and liquid recovery device 6 each have acontroller, and the respective controllers are controlled by maincontroller 20 (refer to FIG. 6). According to instructions from maincontroller 20, the controller of liquid supply device 5 opens the valveconnected to liquid supply pipe 31A to a predetermined degree to supplyliquid (water) to the space between tip lens 191 and wafer W via liquidsupply pipe 31A, the supply flow channel and the supply opening.Further, when the water is supplied, according to instructions from maincontroller 20, the controller of liquid recovery device 6 opens thevalve connected to liquid recovery pipe 31B to a predetermined degree torecover the liquid (water) from the space between tip lens 191 and waferW into liquid recovery device 6 (the liquid tank) via the recoveryopening, the recovery flow channel and liquid recovery pipe 31B. Duringthe supply and recovery operations, main controller 20 gives commands tothe controllers of liquid supply device 5 and liquid recovery device 6so that the quantity of water supplied to the space between tip lens 191and wafer W constantly equals the quantity of water recovered from thespace. Accordingly, a constant quantity of liquid (water) Lq (refer toFIG. 1) is held in the space between tip lens 191 and wafer W. In thiscase, liquid (water) Lq held in the space between tip lens 191 and waferW is constantly replaced.

As is obvious from the above description, in the embodiment, localliquid immersion device 8 is configured including nozzle unit 32, liquidsupply device 5, liquid recovery device 6, liquid supply pipe 31A andliquid recovery pipe 31B, and the like. Incidentally, a part of localliquid immersion device 8, for example, at least nozzle unit 32 may alsobe supported in a suspended state by a main frame (including the barrelplatform previously described) that holds projection unit PU, or mayalso be arranged at another frame member that is separate from the mainframe. Or, in the case projection unit PU is supported in a suspendedstate as is described earlier, nozzle unit 32 may also be supported in asuspended state integrally with projection unit PU, however, in theembodiment, nozzle unit 32 is arranged on a measurement frame that issupported in a suspended state independently from projection unit PU. Inthis case, projection unit PU does not have to be supported in asuspended state.

Incidentally, also in the case measurement stage MST is located belowprojection unit PU, the space between a measurement table (to bedescribed later) and tip lens 191 can be filled with water in thesimilar manner to the manner described above.

Incidentally, in the description above, one liquid supply pipe (nozzle)and one liquid recovery pipe (nozzle) were arranged as an example,however, the present invention is not limited to this, and aconfiguration having multiple nozzles as is disclosed in, for example,the pamphlet of International Publication No. 99/49504, may also beemployed, in the case such an arrangement is possible taking intoconsideration the relation with adjacent members. The point is that anyconfiguration can be employed, as long as the liquid can be supplied inthe space between optical member (tip lens) 191 in the lowest endconstituting projection optical system PL and wafer W. For example, theliquid immersion mechanism disclosed in the pamphlet of InternationalPublication No. 2004/053955, or the liquid immersion mechanism disclosedin the EP Patent Application Publication No. 1420298 can also be appliedto the exposure apparatus of the embodiment.

Referring back to FIG. 1, stage device 50 is equipped with wafer stageWST and measurement stage MST placed above a base board 12, ameasurement system 200 (refer to FIG. 6) which measures positionalinformation of stages WST and MST, a stage drive system 124 (refer toFIG. 6) which drives stages WST and MST and the like. Measurement system200 includes an interferometer system 118, an encoder system 150, and asurface position measurement system 180 as shown in FIG. 6.Incidentally, details on the configuration and the like ofinterferometer system 118, encoder system 150 and the like will bedescribed later in the description.

Referring back to FIG. 1, on each bottom surface of wafer stage WST andmeasurement stage MST, a noncontact bearing (not shown), for example, avacuum preload type hydrostatic air bearing (hereinafter, referred to asan “air pad”) is arranged at a plurality of points, and wafer stage WSTand measurement stage MST are supported in a noncontact manner via aclearance of around several μm above base board 12, by static pressureof pressurized air that is blown out from the air pad toward the uppersurface of base board 12. Further, stages WST and MST are drivableindependently within the XY plane, by stage drive system 124 (refer toFIG. 6) which includes a linear motor and the like.

Wafer stage WST includes a stage main section 91 and a wafer table WTBthat is mounted on stage main section 91. Wafer table WTB and stage mainsection 91 are configured drivable in directions of six degrees offreedom (X, Y, Z, θx, θy, and θz) with respect to base board 12 by adrive system including a linear motor and a Z leveling mechanism (forexample, including a voice coil motor and the like).

On wafer table WTB, a wafer holder (not shown) that holds wafer W byvacuum suction or the like is arranged. The wafer holder may also beformed integrally with wafer table WTB, but in the embodiment, the waferholder and wafer table WTB are separately configured, and the waferholder is fixed inside a recessed portion of wafer table WTB, forexample, by vacuum suction or the like. Further, on the upper surface ofwafer table WTB, a plate (liquid repellent plate) 28 is arranged, whichhas the surface (liquid repellent surface) substantially flush with thesurface of wafer W mounted on the wafer holder to which liquid repellentprocessing with respect to liquid Lq is performed, has a rectangularouter shape (contour), and has a circular opening that is formed in thecenter portion and is slightly larger than the wafer holder (a mountingarea of the wafer). Plate 28 is made of materials with a low coefficientof thermal expansion, such as glass or ceramics (e.g., such as Zerodur(the brand name) of Schott AG, Al₂O₃, or TiC), and on the surface ofplate 28, a liquid repellent film is formed by, for example, fluorineresin materials, fluorine series resin materials such aspolytetrafluoroethylene (Teflon (registered trademark)), acrylic resinmaterials, or silicon series resin materials. Further, as shown in aplanar view of wafer table WTB (wafer stage WST) in FIG. 4A, plate 28has a first liquid repellent area 28 a whose outer shape (contour) isrectangular enclosing a circular opening, and a second liquid repellentarea 28 b that has a rectangular frame (annular) shape placed around thefirst liquid repellent area 28 a. On the first liquid repellent area 28a, for example, at the time of an exposure operation, at least part of aliquid immersion area 14 (for example, refer to FIG. 13) that isprotruded from the surface of the wafer is formed, and on the secondliquid repellent area 28 b, scales for an encoder system (to bedescribed later) are formed. Incidentally, at least part of the surfaceof plate 28 does not have to be on a flush surface with the surface ofthe wafer, that is, may have a different height from that of the surfaceof the wafer. Further, plate 28 may be a single plate, however, in theembodiment, plate 28 is configured by combining a plurality of plates,for example, first and second liquid repellent plates that correspond tothe first liquid repellent area 28 a and the second liquid repellentarea 28 b respectively. In the embodiment, water is used as liquid Lq asis described above, and therefore, hereinafter the first liquidrepellent area 28 a and the second liquid repellent area 28 b are alsoreferred to as a first water repellent plate 28 a and a second waterrepellent plate 28 b.

In this case, exposure light IL is irradiated to the first waterrepellent plate 28 a on the inner side, while exposure light IL ishardly irradiated to the second water repellent plate 28 b on the outerside. Taking this fact into consideration, in the embodiment, a firstwater repellent area to which water repellent coat having sufficientresistance to exposure light IL (light in a vacuum ultraviolet region,in this case) is applied is formed on the surface of the first waterrepellent plate 28 a, and a second water repellent area to which waterrepellent coat having resistance to exposure light IL inferior to thefirst water repellent area is applied is formed on the surface of thesecond water repellent plate 28 b. In general, since it is difficult toapply water repellent coat having sufficient resistance to exposurelight IL (in this case, light in a vacuum ultraviolet region) to a glassplate, it is effective to separate the water repellent plate into twosections, the first water repellent plate 28 a and the second waterrepellent plate 28 b which is the periphery of the first water repellentplate, in the manner described above. Incidentally, the presentinvention is not limited to this, and two types of water repellent coatthat have different resistance to exposure light IL may also be appliedon the upper surface of the same plate in order to form the first waterrepellent area and the second water repellent area. Further, the samekind of water repellent coat may be applied to the first and secondwater repellent areas. For example, only one water repellent area mayalso be formed on the same plate.

Further, as is obvious from FIG. 4A, at the end portion on the +Y sideof the first water repellent plate 28 a, a rectangular cutout is formedin the center portion in the X-axis direction, and a measurement plate30 is embedded inside the rectangular space (inside the cutout) that isenclosed by the cutout and the second water repellent plate 28 b. Afiducial mark FM is formed in the center in the longitudinal directionof measurement plate 30 (on a centerline LL of wafer table WTB), and apair of aerial image measurement slit patterns (slit-shaped measurementpatterns) SL are formed in the symmetrical placement with respect to thecenter of the fiducial mark on one side and the other side in the X-axisdirection of fiducial mark FM. As each of aerial image measurement slitpatterns SL, an L-shaped slit pattern having sides along the Y-axisdirection and X-axis direction, or two linear slit patterns extending inthe X-axis and Y-axis directions respectively can be used, as anexample.

Then, as is shown in FIG. 4B, inside wafer stage WST below each ofaerial image measurement slit patterns SL, an L-shaped housing 36 inwhich an optical system containing an objective lens, a mirror, a relaylens and the like is housed is attached in a partially embedded statepenetrating through part of the inside of wafer table WTB and stage mainsection 91. Housing 36 is arranged in pairs corresponding to the pair ofaerial image measurement slit patterns SL, although omitted in thedrawing.

The optical system inside housing 36 guides illumination light IL thathas been transmitted through aerial image measurement slit pattern SLalong an L-shaped route and emits the light toward a −Y direction.Incidentally, in the following description, the optical system insidehousing 36 is described as a light-transmitting system 36 by using thesame reference code as housing 36 for the sake of convenience.

Moreover, on the upper surface of the second water repellent plate 28 b,multiple grid lines are directly formed in a predetermined pitch alongeach of four sides. More specifically, in areas on one side and theother side in the X-axis direction of second water repellent plate 28 b(both sides in the horizontal direction in FIG. 4A), Y scales 39Y₁ and39Y₂ are formed respectively, and Y scales 39Y₁ and 39Y₂ are eachcomposed of a reflective grating (for example, a diffraction grating)having a periodic direction in the Y-axis direction in which grid lines38 having the longitudinal direction in the X-axis direction are formedin a predetermined pitch along a direction parallel to the Y-axis (theY-axis direction).

Similarly, in areas on one side and the other side in the Y-axisdirection of second water repellent plate 28 b (both sides in thevertical direction in FIG. 4A), X scales 39X₁ and 39X₂ are formedrespectively in a state where the scales are placed between Y scales39Y₁ and 39Y₂, and X scales 39X₁ and 39X₂ are each composed of areflective grating (for example, a diffraction grating) having aperiodic direction in the X-axis direction in which grid lines 37 havingthe longitudinal direction in the Y-axis direction are formed in apredetermined pitch along a direction parallel to the X-axis (the X-axisdirection). As each of the scales, a scale is used that has a reflectivediffraction grating made by, for example, hologram or the like, on thesurface of the second water repellent plate 28 b. In this case, eachscale has gratings made up of narrow slits, grooves or the like that aremarked at a predetermined distance (pitch) as graduations. The type ofdiffraction grating used for each scale is not limited, and not only thediffraction grating made up of grooves or the like that are mechanicallyformed, but also, for example, the diffraction grating that is createdby exposing interference fringe on a photosensitive resin may be used.However, each scale is created by marking the graduations of thediffraction grating, for example, in a pitch between 138 nm to 4 μm, forexample, a pitch of 1 μm on a thin plate shaped glass. These scales arecovered with the liquid repellent film (water repellent film) describedabove. Incidentally, the pitch of the grating is shown much wider inFIG. 4A than the actual pitch, for the sake of convenience. The same istrue also in other drawings.

In this manner, in the embodiment, since the second water repellentplate 28 b itself constitutes the scale, a glass plate with low-thermalexpansion is to be used as the second water repellent plate 28 b.However, the present invention is not limited to this, and a scalemember made up of a glass plate or the like with low-thermal expansionon which a grating is formed may also be fixed on the upper surface ofwafer table WTB, for example, by a plate spring (or vacuum suction) orthe like so as to prevent local shrinkage/expansion. In this case, awater repellent plate to which the same water repellent coat is appliedon the entire surface may be used instead of plate 28. Or, wafer tableWTB may also be formed by materials with a low coefficient of thermalexpansion, and in such a case, a pair of Y scales and a pair of X scalesmay be directly formed on the upper surface of wafer table WTB.

Incidentally, in order to protect the diffraction grating, it is alsoeffective to cover the grating with a glass plate with low thermalexpansion that has water repellency (liquid repellency). In this case,as the glass plate, a plate whose thickness is the same level as thewafer, such as for example, a plate 1 mm thick, can be used, and theplate is set on the upper surface of wafer table WTB so that the surfaceof the glass plate becomes the same height (surface position) as thewafer surface.

Incidentally, a pattern for positioning is arranged for deciding therelative position between an encoder head and a scale near the edge ofeach scale (to be described later). The pattern for positioning isconfigured, for example, from grid lines that have differentreflectivity, and when the encoder head scans the pattern, the intensityof the output signal of the encoder changes. Therefore, a thresholdvalue is determined beforehand, and the position where the intensity ofthe output signal exceeds the threshold value is detected. Then, therelative position between the encoder head and the scale is set, withthe detected position as a reference.

To the −Y edge surface and the −X edge surface of wafer table WTB,mirror-polishing is applied, respectively, and as shown in FIG. 2, areflection surface 17 a and a reflection surface 17 b are formed forinterferometer system 118 which will be described later in thedescription.

Measurement stage MST includes a stage main section 92 driven in the XYplane by a linear motor and the like (not shown), and a measurementtable MTB mounted on stage main section 92. Measurement stage MST isconfigured drivable in at least directions of three degrees of freedom(X, Y, and θz) with respect to base board 12 by a drive system (notshown).

Incidentally, the drive system of wafer stage WST and the drive systemof measurement stage MST are included in FIG. 6, and are shown as stagedrive system 124.

Various measurement members are arranged at measurement table MTB (andstage main section 92). As such measurement members, for example, asshown in FIGS. 2 and 5A, members such as an uneven illuminance measuringsensor 94 that has a pinhole-shaped light-receiving section whichreceives illumination light IL on an image plane of projection opticalsystem PL, an aerial image measuring instrument 96 that measures anaerial image (projected image) of a pattern projected by projectionoptical system PL, a wavefront aberration measuring instrument 98 by theShack-Hartman method that is disclosed in, for example, the pamphlet ofInternational Publication No. 03/065428 and the like are employed. Aswavefront aberration measuring instrument 98, the one disclosed in, forexample, the pamphlet of International Publication No. 99/60361 (thecorresponding EP Patent No. 1,079,223) can also be used.

As uneven illuminance measuring sensor 94, the configuration similar tothe one that is disclosed in, for example, Kokai (Japanese UnexaminedPatent Application Publication) No. 57-117238 (the corresponding U.S.Pat. No. 4,465,368) and the like can be used. Further, as aerial imagemeasuring instrument 96, the configuration similar to the one that isdisclosed in, for example, Kokai (Japanese Unexamined Patent ApplicationPublication) No. 2002-014005 (the corresponding U.S. Patent ApplicationPublication No. 2002/0041377) and the like can be used. Incidentally,three measurement members (94, 96 and 98) are to be arranged atmeasurement stage MST in the embodiment, however, the types and/or thenumber of measurement members are/is not limited to them. As themeasurement members, for example, measurement members such as atransmittance measuring instrument that measures a transmittance ofprojection optical system PL, and/or a measuring instrument thatobserves local liquid immersion device 8, for example, nozzle unit 32(or tip lens 191) or the like may also be used. Furthermore, membersdifferent from the measurement members such as a cleaning member thatcleans nozzle unit 32, tip lens 191 or the like may also be mounted onmeasurement stage MST.

In the embodiment, as can be seen from FIG. 5A, the sensors that arefrequently used such as uneven illuminance measuring sensor 94 andaerial image measuring instrument 96 are placed on a centerline CL(Y-axis passing through the center) of measurement stage MST. Therefore,in the embodiment, measurement using these sensors can be performed bymoving measurement stage MST only in the Y-axis direction without movingthe measurement stage in the X-axis direction.

In addition to each of the sensors described above, an illuminancemonitor that has a light-receiving section having a predetermined areasize that receives illumination light IL on the image plane ofprojection optical system PL may also be employed, which is disclosedin, for example, Kokai (Japanese Unexamined Patent ApplicationPublication) No. 11-016816 (the corresponding U.S. Patent ApplicationPublication No. 2002/0061469) and the like. The illuminance monitor isalso preferably placed on the centerline.

Incidentally, in the embodiment, liquid immersion exposure is performedin which wafer W is exposed with exposure light (illumination light) ILvia projection optical system PL and liquid (water) Lq, and accordinglyuneven illuminance measuring sensor 94 (and the illuminance monitor),aerial image measuring instrument 96 and wavefront aberration measuringinstrument 98 that are used in measurement using illumination light ILreceive illumination light IL via projection optical system PL andwater. Further, only part of each sensor such as the optical system maybe mounted on measurement table MTB (and stage main section 92), or theentire sensor may be placed on measurement table MTB (and stage mainsection 92).

Further, on the +Y edge surface and the −X edge surface of measurementtable MTB, reflection surfaces 19 a and 19 b are formed similar to wafertable WTB previously described (refer to FIGS. 2 and 5A).

As shown in FIG. 5B, a frame-shaped attachment member 42 is fixed to theend surface on the −Y side of stage main section 92 of measurement stageMST. Further, to the end surface on the −Y side of stage main section92, a pair of photodetection systems 44 are fixed in the vicinity of thecenter position in the X-axis direction inside an opening of attachmentmember 42, in the placement capable of facing a pair oflight-transmitting systems 36 described previously. Each ofphotodetection systems 44 is composed of an optical system such as arelay lens, a light receiving element such as a photomultiplier tube,and a housing that houses them. As is obvious from FIGS. 4B and 5B andthe description so far, in the embodiment, in a state where wafer stageWST and measurement stage MST are closer together within a predetermineddistance in the Y-axis direction (including a contact state),illumination light IL that has been transmitted through each aerialimage measurement slit pattern SL of measurement plate 30 is guided byeach light-transmitting system 36 and received by the light-receivingelement of each photodetection system 44. That is, measurement plate 30,light-transmitting systems 36 and photodetection systems 44 constitutean aerial image measurement device 45 (refer to FIG. 6), which issimilar to the one disclosed in Kokai (Japanese Unexamined PatentApplication Publication) No. 2002-014005 (the corresponding U.S. PatentApplication Publication No. 2002/0041377) referred to previously, andthe like.

On attachment member 42, a fiducial bar (hereinafter, shortly referredto as an “FD bar”) 46 which is made up of a bar-shaped member having arectangular sectional shape is arranged extending in the X-axisdirection. FD bar 46 is kinematically supported on measurement stage MSTby a full-kinematic mount structure.

Since FD bar 46 serves as a prototype standard (measurement standard),optical glass ceramics with a low coefficient of thermal expansion, suchas Zerodur (the brand name) of Schott AG are employed as the materials.The flatness degree of the upper surface (the surface) of FD bar 46 isset high to be around the same level as a so-called datum plane plate.Further, as shown in FIG. 5A, a reference grating (for example, adiffraction grating) 52 whose periodic direction is the Y-axis directionis respectively formed in the vicinity of the end portions on one sideand the other side in the longitudinal direction of FD bar 46. The pairof reference gratings 52 is formed placed apart from each other at apredetermined distance L, symmetric to the center in the X-axisdirection of FD bar 46, or more specifically, formed in a symmetricplacement to centerline CL previously described.

Further, on the upper surface of FD bar 46, a plurality of referencemarks M are formed in a placement as shown in FIG. 5A. The plurality ofreference marks M are formed in three-row arrays in the Y-axis directionin the same pitch, and the array of each row is formed being shiftedfrom each other by a predetermined distance in the X-axis direction. Aseach of reference marks M, a two-dimensional mark having a size that canbe detected by a primary alignment system and secondary alignmentsystems (to be described later) is used. Reference mark M may also bedifferent in shape (constitution) from fiducial mark FM, but in theembodiment, reference mark M and fiducial mark FM have the sameconstitution and also they have the same constitution with that of analignment mark of wafer W. Incidentally, in the embodiment, the surfaceof FD bar 46 and the surface of measurement table MTB (which may includethe measurement members described above) are also covered with a liquidrepellent film (water repellent film) severally.

In exposure apparatus 100 of the embodiment, although it is omitted inFIG. 1 from the viewpoint of avoiding intricacy of the drawing, aprimary alignment system AL1 having a detection center at a positionspaced apart from optical axis AX of projection optical system PL at apredetermined distance on the −Y side is actually placed on referenceaxis LV as shown in FIG. 3. Primary alignment system AL1 is fixed to thelower surface of a main frame (not shown) via a support member 54. Onone side and the other side in the X-axis direction with primaryalignment system AL1 in between, secondary alignment systems AL2 ₁ andAL2 ₂, and AL2 ₃ and AL2 ₄ whose detection centers are substantiallysymmetrically placed with respect to straight line LV are severallyarranged. That is, five alignment systems AL1 and AL2 ₁ to AL2 ₄ areplaced so that their detection centers are placed at different positionsin the X-axis direction, that is, placed along the X-axis direction.

As is representatively shown by secondary alignment system AL2 ₄, eachsecondary alignment system AL2 _(n) (n=1 to 4) is fixed to a tip(turning end) of an arm 56 _(n) (n=1 to 4) that can turn around arotation center O as the center in a predetermined angle range inclockwise and anticlockwise directions in FIG. 3. In the embodiment, apart of each secondary alignment system AL2 _(n) (e.g. including atleast an optical system that irradiates an alignment light to adetection area and also leads the light that is generated from a subjectmark within the detection area to a light-receiving element) is fixed toarm 56, and the remaining section is arranged at the main frame thatholds projection unit PU. The X-positions of secondary alignment systemsAL2 ₁, AL2 ₂, AL2 ₃, and AL2 ₄ are severally adjusted by rotating aroundrotation center O as the center. In other words, the detection areas (orthe detection centers) of secondary alignment systems AL2 ₁, AL2 ₂, AL2₃, and AL2 ₄ are independently movable in the X-axis direction.Accordingly, the relative positions of the detection areas of primaryalignment system AL1 and secondary alignment systems AL2 ₁, AL2 ₂, AL2₃, and AL2 ₄ are adjustable in the X-axis direction. Incidentally, inthe embodiment, the X-positions of secondary alignment systems AL2 ₁,AL2 ₂, AL2 ₃, and AL2 ₄ are to be adjusted by the rotation of the arms.However, the present invention is not limited to this, and a drivemechanism that drives secondary alignment systems AL2 ₁, AL2 ₂, AL2 ₃,and AL2 ₄ back and forth in the X-axis direction may also be arranged.Further, at least one of secondary alignment systems AL2 ₁, AL2 ₂, AL2₃, and AL2 ₄ can be moved not only in the X-axis direction but also inthe Y-axis direction. Incidentally, since part of each secondaryalignment system AL2 _(n) is moved by arm 56 _(n), positionalinformation of the part that is fixed to arm 56 _(n) is measurable by asensor (not shown) such as, for example, an interferometer or anencoder. The sensor may only measure position information in the X-axisdirection of secondary alignment system AL2 _(n), or may also be capableof measuring position information in another direction, for example, theY-axis direction and/or the rotation direction (including at least oneof the θx and θy directions).

On the upper surface of each arm 56 _(n), a vacuum pad 58, (n=1 to 4,not shown in FIG. 3, refer to FIG. 6) that is composed of a differentialevacuation type air bearing is arranged. Further, arm 56 _(n) can beturned by a rotation drive mechanism 60, (n=1 to 4, not shown in FIG. 3,refer to FIG. 6) that includes, for example, a motor or the like, inresponse to instructions of main controller 20. Main controller 20activates each vacuum pad 58 _(n) to fix each arm 56 _(n) to a mainframe (not shown) by suction after rotation adjustment of arm 56 _(n).Thus, the state of each arm 56 _(n) after rotation angle adjustment,that is, a desired positional relation between primary alignment systemAL1 and four secondary alignment systems AL2 ₁ to AL2 ₄ is maintained.

Incidentally, in the case a portion of the main frame facing arm 56 _(n)is a magnetic body, an electromagnet may also be employed instead ofvacuum pad 58.

In the embodiment, as each of primary alignment system AL1 and foursecondary alignment systems AL2 ₁ to AL2 ₄, for example, an FIA (FieldImage Alignment) system by an image processing method is used thatirradiates a broadband detection beam that does not expose resist on awafer to a subject mark, and picks up an image of the subject markformed on a light-receiving plane by the reflected light from thesubject mark and an image of an index (an index pattern on an indexplate arranged within each alignment system) (not shown), using animaging device (such as CCD), and then outputs their imaging signals.The imaging signal from each of primary alignment system AL1 and foursecondary alignment systems AL2 ₁ to AL2 ₄ is supplied to maincontroller 20 in FIG. 6, via an alignment signal processing system (notshown).

Incidentally, each of the alignment systems described above is notlimited to the FIA system, and an alignment sensor, which irradiates acoherent detection light to a subject mark and detects a scattered lightor a diffracted light generated from the subject mark or makes twodiffracted lights (e.g. diffracted lights of the same order ordiffracted lights being diffracted in the same direction) generated fromthe subject mark interfere and detects an interference light, cannaturally be used alone or in combination as needed. Further, in theembodiment, five alignment systems AL1 and AL2 ₁ to AL2 ₄ are to befixed to the lower surface of the main frame that holds projection unitPU, via support member 54 or arm 56 _(n). However, the present inventionis not limited to this, and for example, the five alignment systems mayalso be arranged on the measurement frame described earlier.

Next, a configuration and the like of interferometer system 118 (referto FIG. 6), which measures the positional information of wafer stage WSTand measurement stage MST, will be described.

The measurement principle of the interferometer will now be brieflydescribed, prior to describing a concrete configuration of theinterferometer system. The interferometer irradiates a measurement beam(measurement light) on a reflection surface set at a measurement object.The interferometer receives a synthesized light of the reflected lightand a reference beam, and measures the intensity of interference light,which is the reflected light (measurement light) and the reference beammade to interfere with each other, with their polarized directionsarranged. In this case, due to optical path difference ΔL of thereflected light and the reference beam, the relative phase (phasedifference) between the reflected light and the reference beam changesby KΔL. Accordingly, the intensity of the interference light changes inproportion to 1+a·cos(KΔL). In this case, homodyne detection is to beemployed, and the wave number of the measurement light and the referencebeam is the same, expressed as K. Constant a is decided by the intensityratio of the measurement light and the reference beam. In this case, thereflection surface to the reference beam is arranged generally on theprojection unit PU side surface (in some cases, inside theinterferometer unit). The reflection surface of this reference beambecomes the reference position of the measurement. Accordingly, inoptical path difference ΔL, the distance from the reference position tothe reflection surface is reflected. Therefore, if the number of times(the number of fringes) of intensity change of the interference lightwith respect to the change of distance to the reflection surface ismeasured, displacement of the reflection surface provided in themeasurement object can be computed by the product of the counter valueand the measurement unit. The measurement unit is, in the case of aninterferometer of a single-pass method is half the wavelength of themeasurement light, and in the case of an interferometer of thedouble-pass method, one-fourth of the wavelength.

Now, in the case an interferometer of the heterodyne detection method isemployed, wave number K₁ of the measurement light and wave number K₂ ofthe reference beam are slightly different. In this case, when theoptical path length of the measurement light and the reference beam areL₁ and L₂, respectively, the phase difference between the measurementbeam and the reference beam is given KΔL+ΔKL₁, and the intensity of theinterference light changes in proportion to 1+a·cos(KΔL+ΔKL₁). However,optical path difference ΔL=L₁−L₂, ΔK=K₁−K₂, and K=K₂. When optical pathL₂ of the reference beam is sufficiently short, and approximate ΔL≈L₁stands, the intensity of the interference light changes in proportion to1+a·cos [(K+ΔK)ΔL]. As it can be seen from above, the intensity of theinterference light periodically vibrates at a wavelength 2π/K of thereference beam along with the change of optical path difference ΔL, andthe envelope curve of the periodic vibration vibrates (beats) at a longcycle 2π/ΔK. Accordingly, in the heterodyne detection method, thechanging direction of optical path difference ΔL, or more specifically,the displacement direction of the measurement object can be learned fromthe long-period beat.

Incidentally, as a major cause of error of the interferometer, theeffect of temperature fluctuation (air fluctuation) of the atmosphere onthe beam optical path can be considered. Assume that wavelength λ of thelight changes to λ+Δλ by air fluctuation. Because the change of phasedifference KΔL by minimal change Δλ of the wavelength is wave numberK=2π/λ, 2πΔLΔλ/λ² can be obtained. In this case, when wavelength oflight λ=1 μm and minute change Δλ=1 mm, the phase change becomes 2π×100with respect to an optical path difference ΔL=100 mm. This phase changecorresponds to displacement which is 100 times the measurement unit. Inthe case the optical path length which is set is long as is described,the interferometer is greatly affected by the air fluctuation whichoccurs in a short time, and is inferior in short-term stability. In sucha case, it is desirable to use a surface position measurement systemwhich will be described later that has an encoder or a Z head.

Interferometer system 118 includes a Y interferometer 16, Xinterferometers 126, 127, and 128, and Z interferometers 43A and 43B forposition measurement of wafer stage WST, and a Y interferometer 18 andan X interferometer 130 for position measurement of measurement stageMST, as shown in FIG. 2. By severally irradiating a measurement beam onreflection surface 17 a and reflection surface 17 b of wafer table WTBand receiving a reflected light of each beam, Y interferometer 16 and Xinterferometers 126, 127, and 128 (X interferometers 126 to 128 are notshown in FIG. 1, refer to FIG. 2) measure a displacement of eachreflection surface from a reference position (for example, a fixedmirror is placed on the side surface of projection unit PU, and thesurface is used as a reference surface), or more specifically, measurethe positional information of wafer stage WST within the XY plane, andthe positional information that have been measured is supplied to maincontroller 20. In the embodiment, as it will be described later on, aseach interferometer a multiaxial interferometer that has a plurality ofmeasurement axes is used with an exception for a part of theinterferometers.

Meanwhile, to the side surface on the −Y side of stage main section 91,a movable mirror 41 having the longitudinal direction in the X-axisdirection is attached via a kinematic support mechanism (not shown), asshown in FIGS. 4A and 4B. Movable mirror 41 is made of a member which islike a rectangular solid member integrated with a pair of triangularprisms adhered to a surface (the surface on the −Y side) of therectangular solid member. As it can be seen from FIG. 2, movable mirror41 is designed so that the length in the X-axis direction is longer thanreflection surface 17 a of wafer table WTB by at least the spacingbetween the two Z interferometers which will be described later.

To the surface on the −Y side of movable mirror 41, mirror-polishing isapplied, and three reflection surfaces 41 b, 41 a, and 41 c are formed,as shown in FIG. 4B. Reflection surface 41 a configures a part of theedge surface on the −Y side of movable mirror 41, and reflection surface41 a is parallel with the XZ plane and also extends in the X-axisdirection. Reflection surface 41 b configures a surface adjacent toreflection surface 41 a on the +Z side, forming an obtuse angle toreflection surface 41 a, and spreading in the X-axis direction.Reflection surface 41 c configures a surface adjacent to the −Z side ofreflection surface 41 a, and is arranged symmetrically with reflectionsurface 41 b, with reflection surface 41 a in between.

A pair of Z interferometers 43A and 43B (refer to FIGS. 1 and 2) thatirradiates measurement beams on movable mirror 41 is arranged facingmovable mirror 41.

As it can be seen when viewing FIGS. 1 and 2 together, Z interferometers43A and 43B are placed apart on one side and the other side of Yinterferometer 16 in the X-axis direction at a substantially equaldistance and at positions slightly lower than Y interferometer 16,respectively.

From each of the Z interferometers 43A and 433, as shown in FIG. 1,measurement beam B1 along the Y-axis direction is irradiated towardreflection surface 41 b, and measurement beam B2 along the Y-axisdirection is irradiated toward reflection surface 41 c (refer to FIG.4B). In the embodiment, fixed mirror 47B having a reflection surfaceorthogonal to measurement beam B1 sequentially reflected off reflectionsurface 41 b and reflection surface 41 c and a fixed mirror 47A having areflection surface orthogonal to measurement beam B2 sequentiallyreflected off reflection surface 41 c and reflection surface 41 b arearranged, each extending in the X-axis direction at a position distancedapart from movable mirror 41 in the −Y-direction by a predetermineddistance in a state where the fixed mirrors do not interfere withmeasurement beams B1 and B2.

Fixed mirrors 47A and 47B are supported, for example, by the samesupport body (not shown) arranged in the frame (not shown) whichsupports projection unit PU.

Y interferometer 16, as shown in FIG. 2 (and FIG. 13), irradiatesmeasurement beams B4 ₁ and B4 ₂ on reflection surface 17 a of wafertable WTB along a measurement axis in the Y-axis direction spaced apartby an equal distance to the −X side and the +X side from reference axisLV previously described, and by receiving each reflected light, detectsthe position of wafer table WTB in the Y-axis direction (a Y position)at the irradiation point of measurement beams B4 ₁ and B4 ₂.Incidentally, in FIG. 1, measurement beams B4 ₁ and B4 ₂ arerepresentatively shown as measurement beam B4.

Further, Y interferometer 16 irradiates a measurement beam B3 towardreflection surface 41 a along a measurement axis in the Y-axis directionwith a predetermined distance in the Z-axis direction spaced betweenmeasurement beams B4 ₁ and B4 ₂, and by receiving measurement beam B3reflected off reflection surface 41 a, detects the Y position ofreflection surface 41 a (more specifically wafer stage WST) of movablemirror 41.

Main controller 20 computes the Y position (or to be more precise,displacement ΔY in the Y-axis direction) of reflection surface 17 a, ormore specifically, wafer table WTB (wafer stage WST), based on anaverage value of the measurement values of the measurement axescorresponding to measurement beams B4 ₁ and B4 ₂ of Y interferometer 16.Further, main controller 20 computes displacement (yawing amount)Δθz^((Y)) of wafer stage WST in the rotational direction around theZ-axis (the θz direction), based on a difference of the measurementvalues of the measurement axes corresponding to measurement beams B4 ₁and B4 ₂. Further, main controller 20 computes displacement (pitchingamount) Δθx in the θx direction of wafer stage WST, based on the Yposition (displacement ΔY in the Y-axis direction) of reflection surface17 a and reflection surface 41 a.

Further, as shown in FIGS. 2 and 13, X interferometer 126 irradiatesmeasurement beams B5 ₁ and B5 ₂ on wafer table WTB along the dualmeasurement axes spaced apart from a straight line (a reference axis) LHin the X-axis direction that passes the optical axis of projectionoptical system PL by the same distance. And, based on the measurementvalues of the measurement axes corresponding to measurement beams B5 ₁and B5 ₂, main controller 20 computes a position (an X position, or tobe more precise, displacement ΔX in the X-axis direction) of wafer stageWST in the X-axis direction. Further, main controller 20 computesdisplacement (yawing amount) Δθz^((X)) of wafer stage WST in the θzdirection from a difference of the measurement values of the measurementaxes corresponding to measurement beams B5 ₃, and B5 ₂. Incidentally,Δθz^((X)) obtained from X interferometer 126 and Δθz^((Y)) obtained fromY interferometer 16 are equal to each other, and represents displacement(yawing amount) Δθz of wafer stage WST in the θz direction.

Further, as shown in FIGS. 14 and 15, a measurement beam B7 from Xinterferometer 128 is irradiated on reflection surface 17 b of wafertable WTB along a straight line LUL, which is a line connecting anunloading position UP where unloading of the wafer on wafer table WTB isperformed and a loading position LP where loading of the wafer ontowafer table WTB is performed and is parallel to the X-axis. Further, asshown in FIGS. 16 and 17, a measurement beam B6 from X interferometer127 is irradiated on reflection surface 17 b of wafer table WTB along astraight line LA, which passes through the detection center of primaryalignment system AL1 and is parallel to the X-axis.

Main controller 20 can obtain displacement ΔX of wafer stage WST in theX-axis direction from the measurement values of measurement beam B6 of Xinterferometer 127 and the measurement values of measurement beam B7 ofX interferometer 128. However, the placement of the three Xinterferometers 126, 127, and 128 is different in the Y-axis direction.Therefore, X interferometer 126 is used at the time of exposure as shownin FIG. 13, X interferometer 127 is used at the time of wafer alignmentas shown in FIG. 19, and X interferometer 128 is used at the time ofwafer loading shown in FIG. 15 and wafer unloading shown in FIG. 14.

From Z interferometers 43A and 43B previously described, measurementbeams B1 and B2 that proceed along the Y-axis are irradiated towardmovable mirror 41, respectively; as shown in FIG. 1. These measurementbeams B1 and B2 are incident on reflection surfaces 41 b and 41 c ofmovable mirror 41, respectively, at a predetermined angle of incidence(the angle is to be θ/2). Then, measurement beam B1 is sequentiallyreflected by reflection surfaces 41 b and 41 c, and then is incidentperpendicularly on the reflection surface of fixed mirror 47B, whereasmeasurement beam B2 is sequentially reflected by reflection surfaces 41c and 41 b and is incident perpendicularly on the reflection surface offixed mirror 47A. Then, measurement beams B2 and B1 reflected off thereflection surface of fixed mirrors 47A and 47B are sequentiallyreflected by reflection surfaces 41 b and 41 c again, or aresequentially reflected by reflection surfaces 41 c and 41 b again(returning the optical path at the time of incidence oppositely), andthen are received by Z interferometers 43A and 43B.

In this case, when displacement of movable mirror 41 (more specifically,wafer stage WST) in the Z-axis direction is ΔZo and displacement in theY-axis direction is ΔYo, an optical path length change ΔL1 ofmeasurement beam B1 and an optical path length change ΔL2 of measurementbeam B2 can respectively be expressed as in formulas (1) and (2) below.ΔL1=ΔYo×(1+cos θ)+ΔZo×sin θ  (1)ΔL2=ΔYo×(1+cos θ)−ΔZ×sin θ  (2)

Accordingly, from formulas (1) and (2), ΔZo and ΔYo can be obtainedusing the following formulas (3) and (4).ΔZo=(ΔL1−ΔL2)/2 sin θ  (3)ΔYo=(ΔL1+ΔL2)/{2(1−cos θ)}  (4)

Displacements ΔZo and ΔYo above can be obtained with Z interferometers43A and 43B. Therefore, displacement which is obtained using Zinterferometer 43A is to be ΔZoR and ΔYoR, and displacement which isobtained using Z interferometer 4313 is to be ΔZoL and ΔYoL. And thedistance between measurement beams B1 and B2 irradiated by Zinterferometers 43A and 43B, respectively, in the X-axis direction is tobe a distance D (refer to FIG. 2). Under such premises, displacement(yawing amount) Δθz of movable mirror 41 (more specifically, wafer stageWST) in the θz direction and displacement (rolling amount) Δθy in the θydirection can be obtained by the following formulas (5) and (6).Δθz=tan⁻¹{(ΔYoR−ΔYoL)/D}  (5)Δθy=tan⁻¹{(ΔZoL−ΔZoR)/D}  (6)

Accordingly, by using the formulas (3) to (6) above, main controller 20can compute displacement of wafer stage WST in four degrees of freedom,ΔZo, ΔYo, Δθz, and Δθy, based on the measurement results of Zinterferometers 43A and 43B.

In the manner described above, from the measurement results ofinterferometer system 118, main controller 20 can obtain displacement ofwafer stage WST in directions of six degrees of freedom (Z, X, Y, θz,θx, and θy directions).

Incidentally, in the embodiment, a single stage which can be driven insix degrees of freedom was employed as wafer stage WST, however, insteadof this, wafer stage WST can be configured including a stage mainsection 91, which is freely movable within the XY plane, and a wafertable WTB, which is mounted on stage main section 91 and is finelydrivable relatively with respect to stage main section 91 in at leastthe Z-axis direction, the θx direction, and the θy direction, or a waferstage WST can be employed that has a so-called coarse and fine movementstructure where wafer table WTB can be configured finely movable in theX-axis direction, the Y-axis direction, and the θz direction withrespect to stage main section 91. However, in this case, a configurationin which positional information of wafer table WTB in directions of sixdegrees of freedom can be measured by interferometer system 118 willhave to be employed. Also for measurement stage MST, the stage can beconfigured similarly, by a stage main section 92, and a measurementtable MTB, which is mounted on stage main section 92 and has threedegrees of freedom or six degrees of freedom. Further, instead ofreflection surface 17 a and reflection surface 17 b, a movable mirrorconsisting of a plane mirror can be arranged in wafer table WTB.

In the embodiment, however, position information within the XY plane(including the rotation information in the θz direction) of wafer stageWST (wafer table WTB) is mainly measured by an encoder system (to bedescribed later), and the measurement values of interferometers 16, 126,and 127 are secondarily used in cases such as when long-term fluctuation(for example, by temporal deformation or the like of the scales) of themeasurement values of the encoder system is corrected (calibrated).

Incidentally, at least part of interferometer system 118 (such as anoptical system) may be arranged at the main frame that holds projectionunit PU, or may also be arranged integrally with projection unit PU thatis supported in a suspended state as is described above, however, in theembodiment, interferometer system 118 is to be arranged at themeasurement frame described above.

Incidentally, in the embodiment, positional information of wafer stageWST was to be measured with a reflection surface of a fixed mirrorarranged in projection unit PU serving as a reference surface, however,the position to place the reference surface at is not limited toprojection unit PU, and the fixed, mirror does not always have to beused to measure the positional information of wafer stage WST.

Further, in the embodiment, positional information of wafer stage WSTmeasured by interferometer system 118 is not used in the exposureoperation and the alignment operation which will be described later on,and was mainly to be used in calibration operations (more specifically,calibration of measurement values) of the encoder system, however, themeasurement information (more specifically, at least one of thepositional information in directions of five degrees of freedom) ofinterferometer system 118 can be used in, for example, operations suchas the exposure operation and/or the alignment operation. Further, usinginterferometer system 118 as a backup of an encoder system can also beconsidered, which will be explained in detail later on. In theembodiment, the encoder system measures positional information of waferstage WST in directions of three degrees of freedom, or morespecifically, the X-axis, the Y-axis, and the θz directions. Therefore,in the exposure operation and the like, of the measurement informationof interferometer system 118, positional information related to adirection that is different from the measurement direction (the X-axis,the Y-axis, and the θz direction) of wafer stage WST by the encodersystem, such as, for example, positional information related only to theθx direction and/or the θy direction can be used, or in addition to thepositional information in the different direction, positionalinformation related to the same direction (more specifically, at leastone of the X-axis, the Y-axis, and the θz directions) as the measurementdirection of the encoder system can also be used. Further, in theexposure operation and the like, the positional information of waferstage WST in the Z-axis direction measured using interferometer system118 can be used.

In addition, interferometer system 118 (refer to FIG. 6) includes a Yinterferometer 18 and an X interferometer 130 for measuring thetwo-dimensional position coordinates of measurement table MTB. Yinterferometer 18 and X interferometer 130 (X interferometer 130 is notshown in FIG. 1, refer to FIG. 2) irradiate measurement beams onreflection surfaces 19 a and 19 b of measurement table MTB as shown inFIG. 2, and measure the displacement from a reference position of eachreflection surface by receiving the respective reflected lights. Maincontroller 20 receives the measurement values of Y interferometer 18 andX interferometer 130, and computes the positional information (forexample, including at least the positional information in the X-axis andthe Y-axis directions and rotation information in the θz direction) ofmeasurement stage MST.

Incidentally, as the Y interferometer used for measuring measurementtable MTB, a multiaxial interferometer which is similar to Yinterferometer 16 used for measuring wafer stage WST can be used.Further, as the X interferometer used for measuring measurement tableMTB, a two-axis interferometer which is similar to X interferometer 126used for measuring wafer stage WST can be used. Further, in order tomeasure Z displacement, Y displacement, yawing amount, and rollingamount of measurement stage MST, interferometers similar to Zinterferometers 43A and 43B used for measuring wafer stage WST can beintroduced.

Next, the structure and the like of encoder system 150 (refer to FIG. 6)which measures positional information (including rotation information inthe θz direction) of wafer stage WST in the XY plane will be described.

In exposure apparatus 100 of the embodiment, as shown in FIG. 3, fourhead units 62A to 62D of encoder system 150 are placed in a state ofsurrounding nozzle unit 32 on all four sides. In actual, head units 62Ato 62D are fixed to the foregoing main frame that holds projection unitPU in a suspended state via a support member, although omitted in thedrawings such as FIG. 3 from the viewpoint of avoiding intricacy of thedrawings.

As shown in FIG. 3, head units 62A and 62C are placed on the +X side andthe −X side of projection unit PU, with the X-axis direction serving asa longitudinal direction. Head units 62A and 62C are each equipped witha plurality of (five, in this case) Y heads 65 _(i) and 64 _(j) (i,j=1-5) that are placed at a distance WD in the X-axis direction. Moreparticularly, head units 62A and 62C are each equipped with a pluralityof (four, in this case) Y heads (64 ₁ to 64 ₄ or 65 ₂ to 65 ₅) that areplaced on straight line (reference axis) LH which passes through opticalaxis AX of projection optical system PL and is also parallel to theX-axis at distance WD except for the periphery of projection unit PU,and a Y head (64 ₅ or 65 ₁) which is placed at a position apredetermined distance away in the −Y-direction from reference axis LHin the periphery of projection unit PU, or more specifically, on the −Yside of nozzle unit 32. Head units 62A and 62C are each also equippedwith five Z heads which will be described later on. Hereinafter, Y heads65 _(j) and 64 _(i) will also be described as Y heads 65 and 64,respectively, as necessary.

Head unit 62A constitutes a multiple-lens (five-lens, in this case) Ylinear encoder (hereinafter appropriately shortened to “Y encoder” or“encoder”) 70A (refer to FIG. 6) that measures the position of waferstage WST (wafer table WTB) in the Y-axis direction (the Y-position)using Y scale 39Y₁ previously described. Similarly, head unit 62Cconstitutes a multiple-lens (five-lens, in this case) Y linear encoder70C (refer to FIG. 6) that measures the Y-position of wafer stage WST(wafer table WTB) using Y scale 39Y₂ described above. In this case,distance WD in the X-axis direction of the five Y heads (64 _(i) or 65_(j)) (more specifically, measurement beams) that head units 62A and 62Care each equipped with, is set slightly narrower than the width (to bemore precise, the length of grid line 38) of Y scales 39Y₁ and 39Y₂ inthe X-axis direction.

As shown in FIG. 3, head unit 62B is placed on the +Y side of nozzleunit 32 (projection unit PU), and is equipped with a plurality of, inthis case, four X heads 66 ₅ to 66 ₈ that are placed on reference axisLV previously described along Y-axis direction at distance WD. Further,head unit 62D is placed on the −Y side of primary alignment system AL1,on the opposite side of head unit 62B via nozzle unit 32 (projectionunit PU), and is equipped with a plurality of, in this case, four Xheads 66 ₁ to 66 ₄ that are placed on reference axis LV at distance WD.Hereinafter, X heads 66 ₁ to 66 ₈ will also be described as X head 66,as necessary.

Head unit 623 constitutes a multiple-lens (four-lens, in this case) Xlinear encoder (hereinafter, shortly referred to as an “X encoder” or an“encoder” as needed) 703 (refer to FIG. 6) that measures the position inthe X-axis direction (the X-position) of wafer stage WST using X scale39X₁ described above. Further, head unit 62D constitutes a multiple-lens(four-lens, in this case) X encoder 70D (refer to FIG. 6) that measuresthe X-position of wafer stage WST using X scale 39X₂ described above.

Here, the distance between adjacent X heads 66 (measurement beams) thatare equipped in each of head units 62B and 62D is set shorter than awidth in the Y-axis direction of X scales 39X₁ and 39X₂ (to be moreaccurate, the length of grid line 37). Further, the distance between Xhead 66 of head unit 62B farthest to the −Y side and X head 66 of headunit 62D farthest to the +Y side is set slightly narrower than the widthof wafer stage WST in the Y-axis direction so that switching (linkagedescribed below) becomes possible between the two X heads by themovement of wafer stage WST in the Y-axis direction.

In the embodiment, furthermore, head units 62F and 62E are respectivelyarranged a predetermined distance away on the −Y side of head units 62Aand 62C. Although illustration of head units 62E and 62F is omitted inFIG. 3 and the like from the viewpoint of avoiding intricacy of thedrawings, in actual practice, head units 62E and 62F are fixed to theforegoing main frame that holds projection unit PU in a suspended statevia a support member. Incidentally, for example, in the case projectionunit PU is supported in a suspended state, head units 62E and 62F, andhead units 62A to 62D which are previously described can be supported ina suspended state integrally with projection unit PU, or can be arrangedat the measurement frame described above.

Head unit 62E is equipped with four Y heads 67 ₁ to 67 ₄ whose positionsin the X-axis direction are different. More particularly, head unit 62Eis equipped with three Y heads 67 ₁ to 67 ₃ placed on the −X side of thesecondary alignment system AL2 ₁ on reference axis LA previouslydescribed at substantially the same distance as distance WD previouslydescribed, and one Y head 67 ₄ which is placed at a position apredetermined distance (a distance slightly shorter than WD) away on the+X side from the innermost (the +X side) Y head 67 ₃ and is also on the+Y side of the secondary alignment system AL2 ₁ a predetermined distanceaway to the +Y side of reference axis LA.

Head unit 62F is symmetrical to head unit 62E with respect to referenceaxis LV, and is equipped with four Y heads 68 ₁ to 68 ₄ which are placedin symmetry to four Y heads 67 ₁ to 67 ₄ with respect to reference axisLV. Hereinafter, Y heads 67 ₁ to 67 ₄ and 68 ₁ to 68 ₄ will also bedescribed as Y heads 67 and 68, respectively, as necessary. In the caseof an alignment operation and the like which will be described later on,at least one each of Y heads 67 and 68 faces Y scale 39Y₂ and 39Y₁,respectively, and by such Y heads 67 and 68 (more specifically, Yencoders 70C and 70A which are configured by these Y heads 67 and 68),the Y position (and the θz rotation) of wafer stage WST is measured.

Further, in the embodiment, at the time of baseline measurement(Sec-BCHK (interval)) and the like of the secondary alignment systemwhich will be described later on, Y head 67 ₃ and 68 ₂ which areadjacent to the secondary alignment systems AL2 ₁ and AL2 ₄ in theX-axis direction face the pair of reference gratings 52 of FD bar 46,respectively, and by Y heads 67 ₃ and 68 ₂ that face the pair ofreference gratings 52, the Y position of FD bar 46 is measured at theposition of each reference grating 52. In the description below, theencoders configured by Y heads 67 ₃ and 68 ₂ which face a pair ofreference gratings 52, respectively, are referred to as Y linearencoders (also shortly referred to as a “Y encoder” or an “encoder” asneeded) 70E₂ and 70F₂. Further, for identification, Y encoders 70E and70F configured by Y heads 67 and 68 that face Y scales 39Y₂ and 39Y₁described above, respectively, will be referred to as Y encoders 70E₁and 70F₁.

The linear encoders 70A to 70F described above measure the positioncoordinates of wafer stage WST at a resolution of, for example, around0.1 nm, and the measurement values are supplied to main controller 20.Main controller 20 controls the position within the XY plane of waferstage WST based on three measurement values of linear encoders 70A to70D or on three measurement values of encoders 70B, 70D, 70E₁, and 70F₁,and also controls the rotation in the θz direction of FD bar 46 based onthe measurement values of linear encoders 70E₂ and 70F₂.

In exposure apparatus 100 of the embodiment, as shown in FIG. 3, amultipoint focal position detecting system (hereinafter, shortlyreferred to as a “multipoint AF system”) by an oblique incident methodis arranged, which is composed of an irradiation system 90 a and aphotodetection system 90 b, having a configuration similar to the onedisclosed in, for example, Kokai (Japanese Unexamined Patent ApplicationPublication) No. 06-283403 (the corresponding U.S. Pat. No. 5,448,332)and the like. In the embodiment, as an example, irradiation system 90 ais placed on the +Y side of the −X end portion of head unit 62Epreviously described, and photodetection system 90 b is placed on the +Yside of the +X end portion of head unit 62F previously described in astate of opposing irradiation system 90 a.

A plurality of detection points of the multipoint AF system (90 a, 90 b)are placed at a predetermined distance along the X-axis direction on thesurface to be detected. In the embodiment, the plurality of detectionpoints are placed, for example, in the arrangement of a matrix havingone row and M columns (M is a total number of detection points) orhaving two rows and N columns (N is a half of a total number ofdetection points). In FIG. 3, the plurality of detection points to whicha detection beam is severally irradiated are not individually shown, butare shown as an elongate detection area (beam area) AF that extends inthe X-axis direction between irradiation system 90 a and photodetectionsystem 90 b. Because the length of detection area AF in the X-axisdirection is set to around the same as the diameter of wafer W, by onlyscanning wafer W in the Y-axis direction once, position information(surface position information) in the Z-axis direction across the entiresurface of wafer W can be measured. Further, since detection area AF isplaced between liquid immersion area 14 (exposure area IA) and thedetection areas of the alignment systems (AL1, AL2 ₂, and AL2 ₂ to AL2₄) in the Y-axis direction, the detection operations of the multipointAF system and the alignment systems can be performed in parallel. Themultipoint AF system may also be arranged on the main frame that holdsprojection unit PU or the like, however, in the embodiment, the systemwill be arranged on the measurement frame previously described.

Incidentally, the plurality of detection points are to be placed in onerow and M columns, or two rows and N columns, but the number(s) of rowsand/or columns is/are not limited to these numbers. However, in the casethe number of rows is two or more, the positions in the X-axis directionof detection points are preferably made to be different even between thedifferent rows. Moreover, the plurality of detection points is to beplaced along the X-axis direction. However, the present invention is notlimited to this, and all of or some of the plurality of detection pointsmay also be placed at different positions in the Y-axis direction. Forexample, the plurality of detection points may also be placed along adirection that intersects both of the X-axis and the Y-axis. That is,the positions of the plurality of detection points only have to bedifferent at least in the X-axis direction. Further, a detection beam isto be irradiated to the plurality of detection points in the embodiment,but a detection beam may also be irradiated to, for example, the entirearea of detection area AF. Furthermore, the length of detection area AFin the X-axis direction does not have to be nearly the same as thediameter of wafer W.

In the vicinity of detection points located at both ends out of aplurality of detection points of the multipoint AF system (90 a, 90 b),that is, in the vicinity of both end portions of detection area AF,heads 72 a and 72 b, and 72 c and 72 d of surface position sensors for Zposition measurement (hereinafter, shortly referred to as “Z heads”) arearranged each in a pair, in symmetrical placement with respect toreference axis LV. Z heads 72 a to 72 d are fixed to the lower surfaceof a main frame (not shown). Incidentally, Z heads 72 a to 72 d may alsobe arranged on the measurement frame described above or the like.

As Z heads 72 a to 72 d, a sensor head that irradiates a light to wafertable WTB from above, receives the reflected light and measures positioninformation of the wafer table WTB surface in the Z-axis directionorthogonal to the XY plane at the irradiation point of the light, as anexample, a head of an optical displacement sensor (a sensor head by anoptical pickup method), which has a configuration like an optical pickupused in a CD drive device, is used.

Furthermore, head units 62A and 62C previously described arerespectively equipped with Z heads 76 _(j) and 74 _(i) (i, j=1-5), whichare five heads each, at the same X position as Y heads 65 _(j) and 64_(i) (i, j=1-5) that head units 62A and 62C are respectively equippedwith, with the Y position shifted. In this case, Z heads 76 ₃ to 76 ₅and 74 ₁ to 74 ₃, which are three heads each on the outer side belongingto head units 62A and 62C, respectively, are placed parallel toreference axis LH a predetermined distance away in the +Y direction fromreference axis LH. Further, Z heads 76 ₁ and 74 ₅, which are heads onthe innermost side belonging to head units 62A and 62C, respectively,are placed on the +Y side of projection unit PU, and Z heads 76 ₂ and 74₄, which are the second innermost heads are placed on the −Y side of Yheads 65 ₂ and 64 ₄, respectively. And Z heads 76 _(j), 74 _(i) (i,j=1-5), which are five heads each belonging to head unit 62A and 62C,respectively, are placed symmetric to each other with respect toreference axis LV. Incidentally, as each of the Z heads 76 and 74, anoptical displacement sensor head similar to Z heads 72 a to 72 ddescribed above is employed. Incidentally, the configuration and thelike of the Z heads will be described later on.

In this case, Z head 74 ₃ is on a straight line parallel to the Y-axis,the same as is with Z heads 72 a and 72 b previously described.Similarly, Z head 76 ₃ is on a straight line parallel to the Y-axis, thesame as is with Z heads 72 c and 72 d previously described.

Z heads 72 a to 72 d, Z heads 74 ₂ to 74 ₅, and Z heads 76 ₁ to 76 ₅connect to main controller 20 via a signal processing/selection device170 as shown in FIG. 6, and main controller 20 selects an arbitrary Zhead from Z heads 72 a to 72 d, Z heads 74 ₁ to 74 ₅, and Z heads 76 ₁to 76 ₅ via signal processing/selection device 170 and makes the headmove into an operating state, and then receives the surface positioninformation detected by the Z head which is in an operating state viasignal processing/selection device 170. In the embodiment, a surfaceposition measurement system 180 (a part of measurement system 200) thatmeasures positional information of wafer stage WST in the Z-axisdirection and the direction of inclination with respect to the XY planeis configured, including Z heads 72 a to 72 d, Z heads 74 ₁ to 74 ₅, andZ heads 76 ₁ to 76 ₅, and signal processing/selection device 170.

Incidentally, in FIG. 3, measurement stage MST is omitted and a liquidimmersion area that is formed by water Lq held in the space betweenmeasurement stage MST and tip lens 191 is shown by a reference code 14.Further, in FIG. 3, a reference code UP indicates an unloading positionwhere a wafer on wafer table WTB is unloaded, and a reference code LPindicates a loading position where a wafer is loaded on wafer table WTB.In the embodiment, unloading position UP and loading position LP are setsymmetrically with respect to reference axis LV. Incidentally, unloadingposition UP and loading position LP may be the same position.

FIG. 6 shows the main configuration of the control system of exposureapparatus 100. The control system is mainly configured of maincontroller 20 composed of a microcomputer (or workstation) that performsoverall control of the entire apparatus. In memory 34 which is anexternal memory connected to main controller 20, correction informationis stored of measurement instrument systems such as interferometersystem 118, encoder system 150 (encoders 70A to 70F), Z heads 72 a to 72d, 74 ₁ to 74 ₅, 76 ₁ to 76 ₅ and the like. Incidentally, in FIG. 6,various sensors such as uneven illuminance measuring sensor 94, aerialimage measuring instrument 96 and wavefront aberration measuringinstrument 98 that are arranged at measurement stage MST arecollectively shown as a sensor group 99.

Next, the configuration and the like of Z heads 72 a to 72 d, 74 ₁ to 74₅, and 76 ₁ to 76 ₅ will be described, focusing on Z head 72 a shown inFIG. 7 as a representative.

As shown in FIG. 7, Z head 72 a is equipped with a focus sensor FS, asensor main section ZH which houses focus sensor FS, a drive section(not shown) which drives sensor main section ZH in the Z-axis direction,a measurement section ZE which measures displacement of sensor mainsection ZH in the Z-axis direction and the like.

As focus sensor FS, an optical displacement sensor similar to an opticalpickup used in a CD drive device and the like that irradiates a probebeam LB on a measurement target surface S and optically reads thedisplacement of measurement surface S by receiving the reflected lightis used. The configuration and the like of the focus sensor will bedescribed later in the description. The output signal of focus sensor FSis sent to the drive section (not shown).

The drive section (not shown) includes an actuator such as, for example,a voice coil motor, and one of a mover and a stator of the voice coilmotor is fixed to sensor main section ZH, and the other is fixed to apart of a housing (not shown) which houses the sensor main section ZH,measurement section ZE and the like, respectively. The drive sectiondrives sensor main section ZH in the Z-axis direction according to theoutput signals from focus sensor FS so that the distance between sensormain section ZH and measurement target surface S is constantlymaintained (or to be more precise, so that measurement target surface Sis maintained at the best focus position of the optical system of focussensor FS). By this drive, sensor main section ZH follows thedisplacement of measurement target surface S in the Z-axis direction,and a focus lock state is maintained.

As measurement section ZE, in the embodiment, an encoder by thediffraction interference method is used as an example. Measurementsection ZE includes a reflective diffraction grating EG whose periodicdirection is the Z-axis direction arranged on a side surface of asupport member SM fixed on the upper surface of sensor main section ZHextending in the Z-axis direction, and an encoder head EH which isattached to the housing (not shown) facing diffraction grating EG.Encoder head EH reads the displacement of sensor main section ZH in theZ-axis direction by irradiating probe beam EL on diffraction grating EG,receiving the reflection/diffraction light from diffraction grating EGwith a light-receiving element, and reading the deviation of anirradiation point of probe beam EL from a reference point (for example,the origin).

In the embodiment, in the focus lock state, sensor main section ZH isdisplaced in the Z-axis direction so as to constantly maintain thedistance with measurement target surface S as described above.Accordingly, by encoder head EH of measurement section ZE measuring thedisplacement of sensor main section ZH in the Z-axis direction, surfaceposition (Z position) of measurement target surface S is measured.Measurement values of encoder head EH is supplied to main controller 20via signal processing/selection device 170 previously described asmeasurement values of Z head 72 a.

As shown in FIG. 8A, as an example, focus sensor FS includes threesections, an irradiation system FS₁, an optical system FS₂, and aphotodetection system FS₃.

Irradiation system FS₁ includes, for example, a light source LD made upof laser diodes, and a diffraction grating plate (a diffractive opticalelement) ZG placed on the optical path of a laser beam outgoing fromlight source LD.

Optical system FS₂ includes, for instance, a diffraction light of thelaser beam generated in diffraction grating plate ZG, or morespecifically, a polarization beam splitter PBS, a collimator lens CL, aquarter-wave plate (a λ/4 plate) WP, and object lens OL and the likeplaced sequentially on the optical path of probe beam LB₁.

Photodetection system FS₃, for instance, includes a cylindrical lens CYLand a tetrameric light receiving element ZD placed sequentially on areturn optical path of reflected beam LB₂ of probe beam LB₁ onmeasurement target surface S.

According to focus sensor FS, the linearly polarized laser beamgenerated in light source LD of irradiation system FS₁ is irradiated ondiffraction grating plate ZG, and diffraction light (probe beam) LB₁ isgenerated in diffraction grating plate ZG. The central axis (principalray) of probe beam LB₁ is parallel to the Z-axis and is also orthogonalto measurement target surface S.

Then, probe beam LB₁, or more specifically, light having a polarizationcomponent that is a P-polarized light with respect to a separation planeof polarization beam splitter PBS, is incident on optical system FS₂. Inoptical system FS₂, probe beam LB₁ passes through polarization beamsplitter PBS and is converted into a parallel beam at collimator lensCL, and then passes through λ/4 plate WP and becomes a circularpolarized light, which is condensed at object lens OL and is irradiatedon measurement target surface S. Accordingly, at measurement targetsurface S, reflected light (reflected beam) LB₂ occurs, which is acircular polarized light that proceeds inversely to the incoming lightof probe beam LB₁. Then, reflected beam LB₂ traces the optical path ofthe incoming light (probe beam LB₁) the other way around, and passesthrough object lens OL, λ/4 plate WP, collimator lens CL, and thenproceeds toward polarization beam splitter PBS. In this case, becausethe beam passes through λ/4 plate WP twice, reflected beam LB₂ isconverted into an S-polarized light. Therefore, the proceeding directionof reflected beam LB₂ is bent at the separation plane of polarizationbeam splitter PBS, so that it moves toward photodetection system FS₃.

In photodetection system FS₃, reflected beam LB₂ passes throughcylindrical lenses CYL and is irradiated on a detection surface oftetrameric light receiving element ZD. In this case, cylindrical lensesCYL is a “cambered type” lens, and as shown in FIG. 8B, the YZ sectionhas a convexed shape with the convexed section pointing the Y-axisdirection, and as shown also in FIG. 8C, the XY section has arectangular shape. Therefore, the sectional shape of reflected beam LB₂which passes through cylindrical lenses CYL is narrowed asymmetricallyin the Z-axis direction and the X-axis direction, which causesastigmatism.

Tetrameric light receiving element ZD receives reflected beam LB₂ on itsdetection surface. The detection surface of tetrameric light receivingelement ZD has a square shape as a whole, as shown in FIG. 9A, and it isdivided equally into four detection areas a, b, c, and d with the twodiagonal lines serving as a separation line. The center of the detectionsurface will be referred to as O_(ZD).

In this case, in an ideal focus state (a state in focus) shown in FIG.8A, or more specifically, in a state where probe beam LB₁ is focused onmeasurement target surface S₀, the cross-sectional shape of reflectedbeam LB₂ on the detection surface becomes a circle with center O_(ZD)serving as a center, as shown in FIG. 9C.

Further, in the so-called front-focused state (more specifically, astate equivalent to a state where measurement target surface S is atideal position S₀ and tetrameric light receiving element ZD is at aposition shown by reference code 1 in FIGS. 8B and 8C) where probe beamLB₁ focuses on measurement target surface S₁ in FIG. 8A, thecross-sectional shape of reflected beam LB₂ on the detection surfacebecomes a horizontally elongated circle with center O_(ZD) serving as acenter as shown in FIG. 9B.

Further, in the so-called back-focused state (more specifically, a stateequivalent to a state where measurement target surface S is at idealposition S₀ and tetrameric light receiving element ZD is at a positionshown by reference code −1 in FIGS. 8B and 8C) where probe beam LB₁focuses on measurement target surface in FIG. 8A, the cross-sectionalshape of reflected beam LB₂ on the detection surface becomes alongitudinally elongated circle with center O_(ZD) serving as a centeras shown in FIG. 9D.

In an operational circuit (not shown) connected to tetrameric lightreceiving element ZD, a focus error I expressed as in the followingformula (7) is computed and output to the drive section (not shown),with the intensity of light received in the four detection areas a, b,c, and d expressed as Ia, Ib, Ic, and Id, respectively.I=(Ia+Ic)−(Ib+Id)  (7)

Incidentally, in the ideal focus state described above, because the areaof the beam cross-section in each of the four detection areas is equalto each other, focus error I=0 can be obtained. Further, in the frontfocused state described above, according to formula (7), focus errorbecomes I<0, and in the back focused state, according to formula (7),focus error becomes I>0.

The drive section (not shown) receives focus error I from a detectionsection FS₃ within focus sensor FS, and drives sensor main section ZHwhich stored focus sensor FS in the Z-axis direction so as to reproduceI=0. By this operation of the drive section, because sensor main sectionZH is also displaced following Z displacement of measurement targetsurface S, the probe beam focuses on measurement target surface Swithout fail, or more specifically, the distance between sensor mainsection ZH and measurement target surface S is always constantlymaintained (focus lock state is maintained).

Meanwhile, the drive section (not shown) can also drive and positionsensor main section ZH in the Z-axis direction so that a measurementresult of measurement section ZE coincides with an input signal from theoutside of Z head 72 a. Accordingly, the focus of probe beam LB can alsobe positioned at a position different from the actual surface positionof measurement target surface S. By this operation (scale servo control)of the drive section, processes such as return process in the switchingof the Z heads, avoidance process at the time of abnormality generationin the output signals and the like, which will be described later, canbe performed.

In the embodiment, as is previously described, an encoder is adopted asmeasurement section ZE, and encoder head EH is used to read the Zdisplacement of diffraction grating EG set in sensor main section ZH.Because encoder head EH is a relative position sensor which measures thedisplacement of the measurement object (diffraction grating EG) from areference point, it is necessary to determine the reference point. Inthe embodiment, the reference position (for example, the origin) of theZ displacement can be determined by detecting an edge section ofdiffraction grating EG, or in the case a lay out pattern is arranged indiffraction grating EG, by detecting the pattern for positioning. In anycase, reference surface position of measurement target surface S can bedetermined in correspondence with the reference position of diffractiongrating EG, and the Z displacement of measurement target surface S fromthe reference surface position, or more specifically, the position inthe Z-axis direction can be measured. Incidentally, at the start up andthe like of the Z head, such as the start up and the like of exposureapparatus 100, setting of the reference position (for example, theorigin, or more specifically, the reference surface position ofmeasurement target surface S) of diffraction grating EG is executedwithout fail. In this case, because it is desirable for the referenceposition to be set close to the center of the movement range of sensormain section ZH, a drive coil for adjusting the focal position of theoptical system can be arranged to adjust the Z position of object lensOL so that the reference surface position corresponding to the referenceposition around the center coincides with the focal position of theoptical system in the focus sensor FS.

In Z head 72 a, because sensor main section ZH and measurement sectionZE are housed together inside the housing (not shown) and the part ofthe optical path length of probe beam LB₁ which is exposed outside thehousing is extremely short, the influence of air fluctuation isextremely small. Accordingly, even when compared, for example, with alaser interferometer, the sensor including the Z head is much moresuperior in measurement stability (short-term stability) during a periodas short as while the air fluctuates.

The other Z heads are also configured and function in a similar manneras Z head 72 a described above. As is described, in the embodiment, aseach Z head, a configuration is employed where the diffraction gratingsurfaces of Y scales 39Y₁, 39Y₂ and the like are observed from above(the +Z direction) as in the encoder. Accordingly, by measuring thesurface position information of the upper surface of wafer table WTB atdifferent positions with the plurality of Z heads, the position of waferstage WST in the Z-axis direction, the θy rotation (rolling), and the θxrotation (pitching) can be measured. However, in the embodiment, becausethe accuracy of pitching control of wafer stage WST is not especiallyimportant on exposure, the surface position measurement system includingthe Z head does not measure pitching, and a configuration was employedwhere one Z head each faces Y scales 39Y₁ and 39Y₂ on wafer table WTB.

Next, detection of position information (surface position information)of the wafer W surface in the Z-axis direction (hereinafter, referred toas focus mapping) that is performed in exposure apparatus 100 of theembodiment will be described.

On the focus mapping, as is shown in FIG. 10A, main controller 20controls the position within the XY plane of wafer stage WST based on Xhead 66 ₃ facing X scale 39X₂ (X linear encoder 70D) and two Y heads 68₂ and 67 ₃ facing Y scales 39Y₁ and 39Y₂ respectively (Y linear encoders70A and 70C). In the state of FIG. 10A, a straight line (centerline)parallel to the Y-axis that passes through the center of wafer table WTB(which substantially coincides with the center of wafer W) coincideswith reference line LV previously described. Further, although it isomitted in the drawing here, measurement stage MST is located on the +Yside of wafer stage WST, and water is retained in the space between FDbar 46, wafer table WTB and tip lens 191 of projection optical system PLpreviously described (refer to FIG. 18).

Then, in this state, main controller 20 starts scanning of wafer stageWST in the +Y direction, and after having started the scanning,activates (turns ON) both Z heads 72 a to 72 d and the multipoint AFsystem (90 a, 90 b) by the time when wafer stage WST moves in the +Ydirection and detection beams (detection area AF) of the multipoint AFsystem (90 a, 90 b) begin to be irradiated on wafer W.

Then, in a state where Z heads 72 a to 72 d and the multipoint AF system(90 a, 90 b) simultaneously operate, as is shown in FIG. 103, positioninformation (surface position information) of the wafer table WTBsurface (surface of plate 28) in the Z-axis direction that is measuredby Z heads 72 a to 72 d and position information (surface positioninformation) of the wafer W surface in the Z-axis direction at aplurality of detection points that is detected by the multipoint AFsystem (90 a, 90 b) are loaded at a predetermined sampling intervalwhile wafer stage WST is proceeding in the +Y direction, and three kindsof information, which are each surface position information that hasbeen loaded and the measurement values of Y linear encoders 70A and 70Cat the time of each sampling, are made to correspond to one another andare sequentially stored in a memory (not shown).

Then, when the detection beams of the multipoint AF system (90 a, 90 b)begin to miss wafer W, main controller 20 ends the sampling describedabove and converts the surface position information at each detectionpoint of the multipoint AF system (90 a, 90 b) into data which uses thesurface position information by Z heads 72 a to 72 d that has beenloaded simultaneously as a reference.

More specifically, based on an average value of the measurement valuesof Z heads 72 a and 72 b, surface position information at apredetermined point (for example, corresponding to a midpoint of therespective measurement points of Z heads 72 a and 72 b, that is, a pointon substantially the same X-axis as the array of a plurality ofdetection points of the multipoint AF system (90 a, 90 b): hereinafter,this point is referred to as a left measurement point P1) on an area (anarea where Y scale 39Y₂ is formed) near the edge section on the −X sideof plate 28 is obtained. Further, based on an average value of themeasurement values of Z heads 72 c and 72 d, surface positioninformation at a predetermined point (for example, corresponding to amidpoint of the respective measurement points of Z heads 72 c and 72 d,that is, a point on substantially the same X-axis as the array of aplurality of detection points of the multipoint AF system (90 a, 90 b):hereinafter, this point is referred to as a right measurement point P2)on an area (an area where Y scale 39Y₁ is formed) near the edge sectionon the +X side of plate 28 is obtained. Then, as shown in FIG. 10C, maincontroller 20 converts the surface position information at eachdetection point of the multipoint AF system (90 a, 90 b) into surfaceposition data z1-zk, which uses a straight line that connects thesurface position of left measurement point P1 and the surface positionof right measurement point P2 as a reference. Main controller 20performs such a conversion on all information taken in during thesampling.

By obtaining such converted data in advance in the manner describedabove, for example, in the case of exposure, main controller 20 measuresthe wafer table WTB surface (a point on the area where Y scale 39Y₂ isformed (a point near left measurement point P1 described above) and apoint on the area where Y scale 39Y₁ is formed (a point near rightmeasurement point P1 described above)) with Z heads 74 _(i) and 76 _(j)previously described, and computes the Z position and θy rotation(rolling) amount θy of wafer stage WST. Then, by performing apredetermined operation using the Z position, the rolling amount θy, andthe θx rotation (pitching) amount θx of wafer stage WST measured with Yinterferometer 16, and computing the Z position (Z_(o)), rolling amountθy, and pitching amount θx of the wafer table WTB surface in the center(the exposure center) of exposure area IA previously described, and thenobtaining the straight line passing through the exposure center thatconnects the surface position of left measurement point P1 and thesurface position of right measurement point P2 described above based onthe computation results, it becomes possible to perform the surfaceposition control (focus leveling control) of the upper surface of waferW without actually acquiring the surface position information of thewafer W surface by using such straight line and surface position dataz1-zk. Accordingly, because there is no problem even if the multipointAF system is placed at a position away from projection optical systemPL, the focus mapping of the embodiment can suitably be applied also toan exposure apparatus and the like that has a short working distance.

Incidentally, in the description above, while the surface position ofleft measurement point P1 and the surface position of right measurementpoint P2 were computed based on the average value of the measurementvalues of Z heads 72 a and 72 b, and the average value of Z heads 72 cand 72 d, respectively, the surface position information at eachdetection point of the multipoint AF system (90 a, 90 b) can also beconverted, for example, into surface position data which uses thestraight line connecting the surface positions measured by Z heads 72 aand 72 c as a reference. In this case, the difference between themeasurement value of Z head 72 a and the measurement value of Z head 72b obtained at each sampling timing, and the difference between themeasurement value of Z head 72 c and the measurement value of Z head 72d obtained at each sampling timing are to be obtained severally inadvance. Then, when performing surface position control at the time ofexposure or the like, by measuring the wafer table WTB surface with Zheads 74 _(i) and 76 _(j) and computing the Z-position and the θyrotation of wafer stage WST, and performing a predetermined operationusing these computed values, pitching amount θx of wafer stage WSTmeasured by Y interferometer 16, surface position data z1 to zkpreviously described, and the differences described above, it becomespossible to perform surface position control of wafer W, withoutactually obtaining the surface position information of the wafersurface.

However, the description so far is made assuming that unevenness doesnot exist on the wafer table WTB surface in the X-axis direction.Accordingly, hereinafter, to simplify the description, unevenness is notto exist on the wafer table WTB surface in the X-axis direction and theY-axis direction.

Next, focus calibration will be described. Focus calibration refers to aprocess where a processing of obtaining a relation between surfaceposition information of wafer table WTB at end portions on one side andthe other side in the X-axis direction in a reference state anddetection results (surface position information) at representativedetection points on the measurement plate 30 surface of multipoint AFsystem (90 a, 90 b) (former processing of focus calibration), and aprocessing of obtaining surface position information of wafer table WTBat end portions on one side and the other side in the X-axis directionthat correspond to the best focus position of projection optical systemPL detected using aerial image measurement device 45 in a state similarto the reference state above (latter processing of focus calibration)are performed, and based on these processing results, an offset ofmultipoint AF system (90 a, 90 b) at representative detection points, orin other words, a deviation between the best focus position ofprojection optical system PL and the detection origin of the multipointAF system, is obtained.

On the focus calibration, as is shown in FIG. 11A, main controller 20controls the position within the XY plane of wafer stage WST based on Xhead 66 ₂ facing X scale 39X₂ (X linear encoder 70D) and two Y heads 68₂ and 67 ₃ facing Y scales 39Y₁ and 39Y₂ respectively (Y linear encoders70A and 70C). The state of FIG. 11A is substantially the same as thestate in FIG. 10A previously described. However, in the state of FIG.11A, wafer table WTB is at a position where a detection beam frommultipoint AF system (90 a, 90 b) is irradiated on measurement plate 30previously described in the Y-axis direction.

(a) In this state, main controller 20 performs the former processing offocus calibration as in the following description. More specifically,while detecting surface position information of the end portions on oneside and the other side of wafer table WTB in the X-axis direction thatis detected by Z heads 72 a, 72 b, 72 c and 72 d previously describedwhich are in the vicinity of the respective detection points located atboth end sections of the detection area of the multipoint AF system (90a, 90 b), main controller 20 uses the surface position information as areference, and detects surface position information of the measurementplate 30 (refer to FIG. 3) surface previously described using themultipoint AF system (90 a, 90 b). Thus, a relation between themeasurement values of Z heads 72 a, 72 b, 72 c and 72 d (surfaceposition information at end portions on one side and the other side ofwafer table WTB in the X-axis direction) and the detection results(surface position information) at a detection point (the detection pointlocated in the center or the vicinity thereof out of a plurality ofdetection points) on the measurement plate 30 surface of the multipointAF system (90 a, 90 b), in a state where the centerline of wafer tableWTB coincides with reference line LV, is obtained.(b) Next, main controller 20 moves wafer stage WST in the +Y directionby a predetermined distance, and stops wafer stage WST at a positionwhere measurement plate 30 is located directly below projection opticalsystem PL. Then, main controller 20 performs the latter processing offocus calibration as follows. More specifically, as is shown in FIG.11B, while controlling the position of measurement plate 30 (wafer stageWST) in the optical axis direction of projection optical system PL (theZ position), using surface position information measured by Z heads 72 ato 72 d as a reference as in the former processing of focus calibration,main controller 20 measures an aerial image of a measurement mark formedon reticle R or on a mark plate (not shown) on reticle stage RST by a Zdirection scanning measurement whose details are disclosed in, forexample, the pamphlet of International Publication No. 2005/124834 andthe like, using aerial image measurement device 45, and based on themeasurement results, measures the best focus position of projectionoptical system PL. During the Z direction scanning measurement describedabove, main controller 20 takes in measurement values of a pair of Zheads 74 ₃ and 76 ₃ which measure the surface position information atend portions on one side and the other side of wafer table WTB in theX-axis direction, in synchronization with taking in output signals fromaerial image measurement device 45. Then, main controller 20 stores thevalues of Z heads 74 ₃ and 76 ₃ corresponding to the best focus positionof projection optical system PL in memory (not shown). Incidentally, thereason why the position (Z position) related to the optical axisdirection of projection optical system PL of measurement plate 30 (waferstage WST) is controlled using the surface position information measuredin the latter processing of the focus calibration by Z heads 72 a to 72d as a reference is because the latter processing of the focuscalibration is performed during the focus mapping previously described.

In this case, because liquid immersion area 14 is formed betweenprojection optical system PL and measurement plate 30 (wafer table WTB)as shown in FIG. 11B, the measurement of the aerial image is performedvia projection optical system PL and the water. Further, although it isomitted in FIG. 11B, because measurement plate 30 and the like of aerialimage measurement device 45 are installed in wafer stage WST (wafertable WTB), and the light receiving elements are installed inmeasurement stage MST, the measurement of the aerial image describedabove is performed while wafer stage WST and measurement stage MSTmaintain a contact state (or a proximity state) (refer to FIG. 20).

(c) Accordingly, main controller 20 can obtain the offset at therepresentative detection point of the multipoint AF system (90 a, 90 b),or more specifically, the deviation between the best focus position ofprojection optical system PL and the detection origin of the multipointAF system, based on the relation between the measurement values of Zheads 72 a to 72 d (surface position information at the end portions onone side and the other side in the X-axis direction of wafer table WTB)and the detection results (surface position information) of themeasurement plate 30 surface by the multipoint AF system (90 a, 90 b)obtained in (a) described above, in the former processing of focuscalibration, and also on the measurement values of Z heads 74 ₃ and 76 ₃(that is, surface position information at the end portions on one sideand the other side in the X-axis direction of wafer table WTB)corresponding to the best focus position of projection optical system PLobtained in (b) described above, in the latter processing of focuscalibration. In the embodiment, the representative detection point is,for example, the detection point in the center of the plurality ofdetection points or in the vicinity thereof, but the number and/or theposition may be arbitrary. In this case, main controller 20 adjusts thedetection origin of the multipoint AF system so that the offset at therepresentative detection point becomes zero. The adjustment may beperformed, for example, optically, by performing angle adjustment of aplane parallel plate (not shown) inside photodetection system 90 b, orthe detection offset may be electrically adjusted. Alternatively, theoffset may be stored, without performing adjustment of the detectionorigin. In this case, adjustment of the detection origin is to beperformed by the optical method referred to above. This completes thefocus calibration of the multipoint AF system (90 a, 90 b).Incidentally, because it is difficult to make the offset become zero atall the remaining detection points other than the representativedetection point by adjusting the detection origin optically, it isdesirable to store the offset after the optical adjustment at theremaining detection points.

Next, offset correction of detection values among a plurality oflight-receiving elements (sensors) that individually correspond to aplurality of detection points of the multiple AF system (90 a, 90 b)(hereinafter, referred to as offset correction among AF sensors) will bedescribed.

On the offset correction among AF sensors, as is shown in FIG. 12A, maincontroller 20 makes irradiation system 90 a of the multipoint AF system(90 a, 90 b) irradiate detection beams to FD bar 46 equipped with apredetermined reference plane, and takes in output signals fromphotodetection system 90 b of the multipoint AF system (90 a, 90 b) thatreceives the reflected lights from the FD bar 46 surface (referenceplane).

In this case, if the FD bar 46 surface is set parallel to the XY plane,main controller 20 can perform the offset correction among AF sensors byobtaining a relation among the detection values (measurement values) ofa plurality of sensors that individually correspond to a plurality ofdetection points based on the output signals loaded in the mannerdescribed above and storing the relation in a memory, or by electricallyadjusting the detection offset of each sensor so that the detectionvalues of all the sensors become, for example, the same value as thedetection value of a sensor that corresponds to the representativedetection point on the focus calibration described above.

In the embodiment, however, as is shown in FIG. 12A, because maincontroller 20 detects the inclination of the surface of FD bar 46 usingZ heads 74 ₄, 74 ₅, 76 ₁ and 76 ₂ when taking in the output signals fromphotodetection system 90 b of the multipoint AF system (90 a, 90 b), theFD bar 46 surface does not necessarily have to be set parallel to the XYplane. In other words, as is modeled in FIG. 12B, when it is assumedthat the detection value at each detection point is the value asseverally indicated by arrows in the drawing, and the line that connectsthe upper end of the detection values has an unevenness as shown in thedotted line in the drawing, each detection value only has to be adjustedso that the line that connects the upper end of the detection valuesbecomes the solid line shown in the drawing.

Next, a parallel processing operation that uses wafer stage WST andmeasurement stage MST in exposure apparatus 100 of the embodiment willbe described, based on FIGS. 13 to 23. Incidentally, during theoperation below, main controller 20 performs the open/close control ofeach valve of liquid supply device 5 and liquid recovery device 6 oflocal liquid immersion device 8 in the manner previously described, andwater is constantly filled on the outgoing surface side of tip lens 191of projection optical system PL. However, in the description below, forthe sake of simplicity, the explanation related to the control of liquidsupply device 5 and liquid recovery device 6 will be omitted. Further,many drawings are used in the operation description hereinafter,however, reference codes may or may not be given to the same member foreach drawing. More specifically, the reference codes written aredifferent for each drawing, however, such members have the sameconfiguration, regardless of the indication of the reference codes. Thesame can be said for each drawing used in the description so far.

FIG. 13 shows a state in which an exposure by the step-and-scan methodof wafer W mounted on wafer stage WST is performed. This exposure isperformed by alternately repeating a movement between shots in whichwafer stage WST is moved to a scanning starting position (accelerationstaring position) to expose each shot area on wafer W and scanningexposure in which the pattern formed on reticle R is transferred ontoeach shot area by the scanning exposure method, based on results ofwafer alignment (EGA: Enhanced Global Alignment) and the like which hasbeen performed prior to the beginning of exposure. Further, exposure isperformed in the following order, from the shot area located on the −Yside on wafer W to the shot area located on the +Y side. Incidentally,exposure is performed in a state where liquid immersion area 14 isformed in between projection unit PU and wafer W.

During the exposure described above, the position (including rotation inthe θz direction) of wafer stage WST (wafer table WTB) in the XY planeis controlled by main controller 20, based on measurement results of atotal of three encoders which are the two Y encoders 70A and 70C, andone of the two X encoders 70B and 70D. In this case, the two X encoders70B and 70D are made up of two X heads 66 that face X scale 39X₁ and39X₂, respectively, and the two Y encoders 70A and 70C are made up of Yheads 65 and 64 that face Y scales 39Y₁ and 39Y₂, respectively. Further,the Z position and rotation (rolling) in the θy direction of wafer stageWST are controlled, based on measurement results of Z heads 74 _(i) and76 _(j), which respectively belong to head units 62C and 62A facing theend section on one side and the other side of the surface of wafer tableWTB in the X-axis direction, respectively. The θx rotation (pitching) ofwafer stage WST is controlled based on measurement values of Yinterferometer 16. Incidentally, in the case three or more Z headsincluding Z head 74 _(i) and 76 _(i) face the surface of the secondwater repellent plate 28 b of wafer table WTB, it is also possible tocontrol the position of wafer stage WST in the Z-axis direction, the θyrotation (rolling), and the θx rotation (pitching), based on themeasurement values of Z heads 74 _(i), 76 _(i) and the other one head.In any case, the control (more specifically, the focus leveling controlof wafer W) of the position of wafer stage WST in the Z-axis direction,the rotation in the θy direction, and the rotation in the θx directionis performed, based on results of a focus mapping performed beforehand.

At the position of wafer stage WST shown in FIG. 13, while X head 66 ₅(shown circled in FIG. 13) faces X scale 39X₁, there are no X heads 66that face X scale 39X₂. Therefore, main controller 20 uses one X encoder70B and two Y encoders 70A and 70C so as to perform position (X, Y, θz)control of wafer stage WST. In this case, when wafer stage WST movesfrom the position shown in FIG. 13 to the −Y direction, X head 66 ₅moves off of (no longer faces) X scale 39X₁, and X head 66 ₄ (showncircled in a broken line in FIG. 13) faces X scale 39X₂ instead.Therefore, main controller 20 switches the control to a position (X, Y,θz) control of wafer stage WST that uses one X encoder 70D and two Yencoders 70A and 70C.

Further, when wafer stage WST is located at the position shown in FIG.13, Z heads 74 ₃ and 76 ₃ (shown circled in FIG. 13) face Y scales 39Y₂and 39Y₁, respectively. Therefore, main controller 20 performs position(Z, θy) control of wafer stage WST using Z heads 74 ₃ and 76 ₃. In thiscase, when wafer stage WST moves from the position shown in FIG. 13 tothe +X direction, Z heads 74 ₃ and 76 ₃ move off of (no longer faces)the corresponding Y scales, and Z heads 74 ₄ and 76 ₄ (shown circled ina broken line in FIG. 13) respectively face Y scales 39Y₂ and 39Y₁instead. Therefore, main controller 20 switches to position (Z, θy)control of wafer stage WST using Z heads 74 ₄ and 76 ₄.

In this manner, main controller 20 performs position control of waferstage WST by consistently switching the encoder and Z heads to usedepending on the position coordinate of wafer stage WST.

Incidentally, independent from the position measurement of wafer stageWST described above using the measuring instrument system describedabove, position (X, Y, Z, θx, θy, θz) measurement of wafer stage WSTusing interferometer system 118 is constantly performed. In this case,the X position and θz rotation (yawing) of wafer stage WST or the Xposition are measured using X interferometers 126, 127, or 128, the Yposition, the ex rotation, and the θz rotation are measured using Yinterferometer 16, and the Y position, the Z position, the θy rotation,and the θz rotation are measured using Z interferometers 43A and 43B(not shown in FIG. 13, refer to FIG. 1 or 2) that constituteinterferometer system 118. Of X interferometers 126, 127, and 128, oneinterferometer is used according to the Y position of wafer stage WST.As indicated in FIG. 13, X interferometer 126 is used during exposure.The measurement results of interferometer system 118 except for pitching(θx rotation) are used for position control of wafer stage WSTsecondarily, or in the case of backup which will be described later on,or when measurement using encoder system 150 cannot be performed.

When exposure of wafer W has been completed, main controller 20 driveswafer stage WST toward unloading position UP. On this drive, wafer stageWST and measurement stage MST which were apart during exposure come intocontact or move close to each other with a clearance of around 300 μm inbetween, and shift to a scrum state. In this case, the −Y side surfaceof FD bar 46 on measurement table MTB and the +Y side surface of wafertable WTB come into contact or move close together. And by moving bothstages WST and MST in the −Y direction while maintaining the scrumcondition, liquid immersion area 14 formed under projection unit PUmoves to an area above measurement stage MST. For example, FIGS. 14 and15 show the state after the movement.

When wafer stage WST moves further to the −Y direction and moves offfrom the effective stroke area (the area in which wafer stage WST movesat the time of exposure and wafer alignment) after the drive of waferstage WST toward unloading position. UP has been started, all the Xheads and Y heads, and all the Z heads that constitute encoder 70A to70D move off from the corresponding scale on wafer table WTB. Therefore,position control of wafer stage WST based on the measurement results ofencoders 70A to 70D and the Z heads is no longer possible. Just beforethis, main controller 20 switches the control to a position control ofwafer stage WST based on the measurement results of interferometersystem 118. In this case, of the three X interferometers 126, 127, and128, X interferometer 128 is used.

Then, wafer stage WST releases the scrum state with measurement stageMST, and then moves to unloading position UP as shown in FIG. 14. Afterthe movement, main controller 20 unloads wafer W on wafer table WTB. Andthen, main controller 20 drives wafer stage WST in the +X direction toloading position LP, and the next wafer W is loaded on wafer table WTBas shown in FIG. 15.

In parallel with these operations, main controller 20 performs Sec-BCHK(a secondary base line check) in which position adjustment of FD bar 46supported by measurement stage MST in the XY plane and baselinemeasurement of the four secondary alignment system AL2 ₁ to AL2 ₄ areperformed. Sec-BCHK is performed on an interval basis for every waferexchange. In this case, in order to measure the position (the θzrotation) in the XY plane, Y encoders 70E₂ and 70F₂ previously describedare used.

Next, as shown in FIG. 16, main controller 20 drives wafer stage WST andpositions reference mark FM on measurement plate 30 within a detectionfield of primary alignment system AL1, and performs the former processof Pri-BCHK (a primary baseline check) in which the reference positionis decided for baseline measurement of alignment system AL1, and AL2 ₁to AL2 ₄.

On this process, as shown in FIG. 16, two Y heads 68 ₂ and 67 ₃ and oneX head 66 ₁ (shown circled in the drawing) come to face Y scales 39Y₁and 39Y₂, and X scale 39X₂, respectively. Then, main controller 20switches the stage control from a control using interferometer system118, to a control using encoder system 150 (encoders 70A, 70C, and 70D).Interferometer system 118 is used secondarily again, except inmeasurement of the θx rotation. Incidentally, of the three Xinterferometers 126, 127, and 128, X interferometer 127 is used.

Next, while controlling the position of wafer stage WST based on themeasurement values of the three encoders described above, maincontroller 20 begins the movement of wafer stage WST in the +Y directiontoward a position where an alignment mark arranged in three firstalignment shot areas is detected.

Then, when wafer stage WST reaches the position shown in FIG. 17, maincontroller 20 stops wafer stage WST. Prior to this operation, maincontroller 20 activates (turns ON) Z heads 72 a to 72 d and startsmeasurement of the Z-position and the tilt (the θy rotation) of waferstage WST at the point in time when all of or part of Z heads 72 a to 72d face (s) wafer table WTB, or before that point in time.

After wafer stage WST is stopped, main controller 20 detects the threealignment marks arranged in the first alignment shot area substantiallyat the same time and also individually (refer to the star-shaped marksin FIG. 17), using primary alignment system AL1, and secondary alignmentsystems AL2 ₂ and AL2 ₃, and makes a link between the detection resultsof the three alignment systems AL1, AL2 ₂, and AL2 ₃ and the measurementvalues of the three encoders above at the time of the detection, andstores them in memory (not shown).

As in the description above, in the embodiment, the shift to the contactstate (or proximity state) between measurement stage MST and wafer stageWST is completed at the position where detection of the alignment marksof the first alignment shot area is performed. And from this position,main controller 20 begins to move both stages WST and MST in the +Ydirection (step movement toward the position for detecting the fivealignment marks arranged in the second alignment shot area) in thecontact state (or proximity state). Prior to starting the movement ofboth stages WST and MST in the +Y direction, as shown in FIG. 17, maincontroller 20 begins irradiation of a detection beam from the multipointAF system (90 a, 90 b) to wafer table WTB. Accordingly, a detection areaof the multipoint AF system is formed on wafer table WTB.

Then, when both stages WST and MST reach the position shown in FIG. 18during the movement of both stages WST and MST in the +Y direction, maincontroller 20 performs the former process of the focus calibration, andobtains the relation between the measurement values (surface positioninformation on one side and the other side of wafer table WTB in theX-axis direction) of Z heads 72 a, 72 b, 72 c, and 72 d, in a statewhere the center line of wafer table WTB coincides with reference axisLV, and the detection results (surface position information) of thesurface of measurement plate 30 by the multipoint AF system (90 a, 90b). At this point, liquid immersion area 14 is formed on the uppersurface of FD bar 46.

Then, both stages WST and MST move further in the +Y direction whilemaintaining the contact state (or proximity state), and reach theposition shown in FIG. 19. Then, main controller 20 detects thealignment mark arranged in the five second alignment shot areassubstantially at the same time as well as individually (refer to thestar-shaped marks in FIG. 19), using the five alignment systems AL1, andAL2 ₁ to AL2 ₄, and makes a link between the detection results of thefive alignment systems AL1, and AL2 ₁ to AL2 ₄ and the measurementvalues of the three encoders measuring the position of wafer stage WSTin the XY plane at the time of the detection, and then stores them inmemory (not shown) (or in memory 34). At this point, main controller 20controls the position within the XY plane of wafer stage WST based onthe measurement values of X head 66 ₂ (X linear encoder 70D) that facesX scale 39X₂ and Y linear encoders 70F₁ and 70E₁.

Further, after the simultaneous detection of the alignment marksarranged in the five second alignment shot areas ends, main controller20 starts again movement in the +Y direction of both stages WST and MSTin the contact state (or proximity state), and at the same time, startsthe focus mapping previously described using Z heads 72 a to 72 d andthe multipoint AF system (90 a, 90 b), as is shown in FIG. 19.

Then, when both stages WST and MST reach the position shown in FIG. 20where measurement plate 30 is located directly below projection opticalsystem PL, main controller 20 performs the latter processing of focuscalibration in a state continuing the control of Z position of waferstage WST (measurement plate 30) that uses the surface positioninformation measured by Z heads 72 a to 72 d as a reference, withoutswitching the Z head used for position (Z position) control of waferstage WST in the optical axis direction of projection optical system PLto Z heads 74 _(i) and 76 _(j).

Then, main controller 20 obtains the offset at the representativedetection point of the multipoint AF system (90 a, 90 b) in theprocedure described above, based on the results of the former processingand latter processing of focus calibration described above, and storesthe offset in the memory (not shown). And, on reading mappinginformation obtained from the results of focus mapping at the time ofexposure, main controller 20 is to add the offset to the mappinginformation.

Incidentally, in the state of FIG. 20, the focus mapping is beingcontinued.

When wafer stage WST reaches the position shown in FIG. 21 by themovement of both stages WST and MST in the contact state (or, proximitystate), to the +Y direction, main controller 20 stops wafer stage WST atthe position, and it makes just continue the movement to the +Ydirection about measurement stage MST. Then, main controller 20 detectsthe alignment mark arranged in the five third alignment shot areassubstantially at the same time as well as individually (refer to thestar-shaped marks in FIG. 21), using the five alignment systems AL1, andAL2 ₁ to AL2 ₄, and makes a link between the detection results of thefive alignment systems AL1, and AL2 ₁ to AL2 ₄ and the measurementvalues of the three encoders at the time of the detection, and thenstores them in the memory (not shown). Also at this point in time, thefocus mapping is being continued.

Meanwhile, after a predetermined period of time from the suspension ofwafer stage WST described above, measurement stage MST and wafer stageWST move from the contact state (or proximity state) into a separationstate. After moving into the separation state, main controller 20 stopsthe movement of measurement stage MST when measurement stage MST reachesan exposure start waiting position where measurement stage MST waitsuntil exposure is started.

Next, main controller 20 starts the movement of wafer stage WST in the+Y direction toward a position where the alignment mark arranged in thethree fourth alignment shots are detected. At this point in time, thefocus mapping is being continued. Meanwhile, measurement stage MST iswaiting at the exposure start waiting position described above.

Then, when wafer stage WST reaches the position shown in FIG. 22, maincontroller 20 immediately stops wafer stage WST, and almostsimultaneously and individually detects the alignment marks arranged inthe three fourth alignment shot areas on wafer W (refer to star-shapedmarks in FIG. 22) using primary alignment system AL1 and secondaryalignment systems AL2 ₂ and AL2 ₃, links the detection results of threealignment systems AL1, AL2 ₂ and AL2 ₃ and the measurement values of thethree encoders out of the four encoders above at the time of thedetection, and stores them in memory (not shown). Also at this point intime, the focus mapping is being continued, and measurement stage MST isstill waiting at the exposure start waiting position. Then, using thedetection results of a total of 16 alignment marks and the measurementvalues of the corresponding encoders obtained in the manner describedabove, main controller 20 computes array information (coordinate values)of all the shot areas on wafer W on an alignment coordinate system (anXY coordinate system whose origin is placed at the detection center ofprimary alignment system AL1) that is set by the measurement axes ofencoders 70B, 70D, 70E₁, and 70F₁ of encoder system 150, by performing astatistical computation disclosed in, for example, Kokai (JapanesePatent Unexamined Application Publication) No. 61-44429 (and thecorresponding U.S. Pat. No. 4,780,617) and the like.

Next, main controller 20 continues the focus mapping while moving waferstage WST in the +Y direction again. Then, when the detection beam fromthe multipoint AF system (90 a, 90 b) begins to miss the wafer Wsurface, as is shown in FIG. 23, main controller 20 ends the focusmapping.

After the focus mapping has been completed, main controller 20 moveswafer table WTB (wafer stage WST) to a scanning starting position(acceleration starting position) for exposure of the first shot on waferW, and during the movement, main controller 20 switches the Z heads usedfor control of the Z position and the θy rotation of wafer stage WSTfrom Z heads 72 a to 72 d to Z heads 74 _(i) and 74 _(i) whilemaintaining the Z position, the θy rotation, and the θx rotation ofwafer stage WST. After this switching, based on the results of the waferalignment (EGA) previously described and the latest baselines and thelike of the five alignment systems AL1 and AL2 ₁ to AL2 ₄, maincontroller 20 performs exposure by a step-and-scan method in a liquidimmersion exposure, and sequentially transfers a reticle pattern to aplurality of shot areas on wafer W. Hereinafter, a similar operation isexecuted repeatedly.

Next, a computation method of the Z position and the amount of tilt ofwafer stage WST using the measurement results of the Z heads will bedescribed. Main controller 20 uses the four Z heads 70 a to 70 d thatconstitute surface position measurement system 180 (refer to FIG. 6) atthe time of focus calibration and focus mapping, and measures height Zand tilt (rolling) θy of wafer table WTB. Further, main controller 20uses two Z heads 74 _(i) and 76 _(i) (i and j are one of 1 to 5) at thetime of exposure, and measures height Z and tilt (rolling) θ_(y) ofwafer table WTB. Incidentally, each Z head irradiates a probe beam onthe upper surface (a surface of a reflection grating formed on the uppersurface) of the corresponding Y scales 39Y₁ or 39Y₂, and measures thesurface position of each scale (reflection grating) by receiving thereflected light.

FIG. 24A shows a two-dimensional plane having height Z₀, rotation angle(an angle of inclination) around the X-axis θx, and rotation angle (anangle of inclination) around the Y-axis θy at a reference point O.Height Z at position (X, Y) of this plane is given by a functionaccording to the next formula (8).f(X,Y)=−tan θy·X+tan θx·Y+Z ₀  (8)

As shown in FIG. 24B, at the time of the exposure, height Z from amovement reference surface (a surface that is substantially parallel tothe XY plane) of wafer table WTB and rolling θy are measured at anintersection point (reference point) O of a movement reference surfaceof wafer table WTB and optical axis AX of projection optical system PL,using two Z heads 74 _(i) and 76 _(j) (i and i are one of 1 to 5). Inthis case, Z heads 74 ₃ and 76 ₃ are used as an example. Similar to theexample shown in FIG. 24A, the height of wafer table WTB at referencepoint O will be expressed as Z₀, the tilt (pitching) around the X-axiswill be expressed as θx, and the tilt (rolling) around the Y-axis willbe expressed as θy. In this case, measurement values Z_(L) and Z_(R) ofthe surface position of (reflection gratings formed on) Y scales 39Y₁and 39Y₂ indicated by Z head 74 ₃, which is located at coordinate(p_(L), q_(L)), and Z head 76 ₃, which is located at coordinate (p_(R),q_(R)), in the XY plane, respectively, follow theoretical formulas (9)and (10), similar to formula (8).Z _(L)=−tan θy·p _(L)+tan θx·q _(L) +Z ₀  (9)Z _(R)=−tan θy·p _(R)+tan θx·q _(R) +Z ₀  (10)

Accordingly, from theoretical formulas (9) and (10), height Z₀ androlling θy of wafer table WTB at reference point O can be expressed asin the following formulas (11) and (12), using measurement values Z_(L)and Z_(R) of Z heads 74 ₃ and 76 ₃.Z ₀ ={Z _(L) +Z _(R)−tan θx·(q _(L) +q _(R))}/2  (11)tan θy={Z _(L) −Z _(R)−tan θx·(q _(L) −q _(R))}/(p _(R) −p _(L))  (12)

Incidentally, in the case of using other combinations of Z heads aswell, by using theoretical formulas (11) and (12), height Z₀ and rollingθy of wafer table WTB at reference point O can be computed. However,pitching θx uses the measurement results of another sensor system (inthe embodiment, interferometer system 118).

As shown in FIG. 24B, at the time of focus calibration and focusmapping, height Z and rolling By of wafer table WTB at a center point O′of a plurality of detection points of the multipoint AF system (90 a, 90b) are measured, using four Z heads 72 a to 72 d. Z heads 72 a to 72 d,in this case, are respectively placed at position (X, Y)=(p_(a), q_(a))(p_(b), q_(b)), (p_(c), q_(c)), (p_(d), q_(d)). As shown in FIG. 24B,these positions are set symmetric to center point O′=(Ox′, Oy′), or morespecifically, p_(a)=p_(b), p_(c)=p_(d), q_(a)=q_(d), and also(p_(a)+p_(c))/2=(p_(b)+p_(d))/2=Ox′,(q_(a)+q_(b))/2=(q_(c)+q_(d))/2=Oy′.

From average (Za+Zb)/2 of measurement values Za and Zb of Z head 72 aand 72 b, height Ze of wafer table WTB at a point e of position(p_(a)=p_(b), Oy′) can be obtained, and from average (Zc+Zd)/2 of themeasurement values Zc and Zd of Z heads 70 c and 70 d, height Zf ofwafer table WTB at a point f of position (p_(c)=p_(d), Oy′) can beobtained. In this case, when the height of wafer table WTB at centerpoint O′ is expressed as Z₀, and the tilt (rolling) around the Y-axis isexpressed as θy, then, Ze and Zf follow theoretical formulas (13) and(14), respectively.Ze{=(Za+Zb)/2}=−tan θy·(p _(a) +p _(b)−2Ox′)/2+Z ₀  (13)Zf{=(Zc+Zd)/2}=−tan θy·(p _(c) +p _(d)−2Ox′)/2+Z ₀  (14)

Accordingly, from theoretical formulas (13) and (14), height Z₀ of wafertable WTB and rolling θy at center point O′ can be expressed as in thefollowing formulas (15) and (16), using measurement values Za to Zd of Zheads 70 a to 70 d.

$\begin{matrix}{Z_{0} = {{( {{Ze} + {Zf}} )/2} = {( {{Za} + {Zb} + {Zc} + {Zd}} )/4}}} & (15) \\\begin{matrix}{{\tan\;\theta\; y} = {{- 2}{( {{Ze} - {Zf}} )/( {p_{a} + p_{b} - p_{c} - p_{d}} )}}} \\{= {{- ( {{Za} + {Zb} - {Zc} - {Zd}} )}/( {p_{a} + p_{b} - p_{c} - p_{d}} )}}\end{matrix} & (16)\end{matrix}$

However, pitching θx uses the measurement results of another sensorsystem (in the embodiment, interferometer system 118).

As shown in FIG. 16, immediately after switching from servo control ofwafer stage WST by interferometer system 118 to servo control by encodersystem 150 (encoders 70A to 70F) and surface position measurement system180 (Z head systems 72 a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅),because only two heads, Z heads 72 b and 72 d, face the corresponding Yscales 39Y₁ and 39Y₂, the Z and By positions of wafer table WTB atcenter point O′ cannot be computed using formulas (15) and (16). In sucha case, the following formulas (17) and (18) are applied.Z ₀ ={Z _(b) +Z _(d)−tan θx·(q _(b) +q _(d)−2Oy′)}/2  (17)tan θy={Z _(b) −Z _(d)−tan θx·(q _(b) −q _(d))}/(p _(d) −p _(b))  (18)

Then, when wafer stage WST has moved in the +Z direction, andaccompanying this move, after Z heads 72 a and 72 c have faced thecorresponding Y scales 39Y₁ and 39Y₂, formulas (15) and (16) above areapplied.

As previously described, scanning exposure to wafer W is performed,after finely driving wafer stage WST in the Z-axis direction and tiltdirection according to the unevenness of the surface of wafer W, andhaving adjusted the surface position of wafer W and the tilt (focusleveling) so that the exposure area IA portion on the surface of wafer Wmatches within the range of the depth of focus of the image plane ofprojection optical system PL. Therefore, prior to the scanning exposure,focus mapping to measure the unevenness (a focus map) of the surface ofwafer W is performed. In this case, as shown in FIG. 10, the unevennessof the surface of wafer W is measured at a predetermined samplinginterval (in other words, a Y interval) while moving wafer stage WST inthe +Y direction, using the multipoint AF system (90 a, 90 b) with thesurface position of wafer table WTB (or to be more precise, thecorresponding Y scales 39Y₁ and 39Y₂) measured using Z heads 72 a to 72d serving as a reference.

To be specific, as shown in FIG. 24B, surface position Ze of wafer tableWTB at point e can be obtained from the average of surface positions Zaand Zb of Y scale 39Y₂, which is measured using Z heads 72 a and 72 b,and surface position Zf of wafer table WTB at point f can be obtainedfrom the average of surface positions Zc and Zd of Y scale 39Y₁, whichis measured using Z heads 72 c and 72 d. In this case, the plurality ofdetection points of the multipoint AF system and center O′ of thesepoints are located on a straight line of parallel to the X-axis andconnecting point e and point f. Therefore, as shown in FIG. 10C, byusing a straight line expressed in the following formula (19) connectingsurface position Ze at point e (P1 in FIG. 10C) of wafer table WTB andsurface position Zf at point f (P2 in FIG. 10C) as a reference, surfaceposition Z_(0k) of the surface of wafer W at detection point X_(k) ismeasured, using the multipoint AF system (90 a, 90 b).Z(X)=−tan θy·X+Z ₀  (19)

However, Z₀ and tan θy can be obtained from formulas (17) and (18)above, using measurement results Za to Zd of Z heads 72 a to 72 d. Fromthe results of surface position Z_(ok) that has been obtained,unevenness data (focus map) Z_(k) of the surface of wafer W can beobtained as in the following formula (20).Z _(k) =Z _(ok) −Z(X _(k))  (20)

At the time of exposure, by finely driving wafer stage WST in the Z-axisdirection and the tilt direction according to focus map Z_(k) obtainedin the manner described above, focus is adjusted for each shot area, asis previously described. At the time of the exposure here, the surfaceposition of wafer table WTB (or to be more precise, the corresponding Yscales 39Y₂ and 39Y₁) is measured, using Z heads 74 _(i) and 76 _(j) (i,j=1-5). Therefore, reference line Z (X) of focus map Z_(k) is set again.However, Z₀ and tan θy can be obtained from formulas (II) and (12)above, using the measurement results Z₁ and Z_(R) of Z heads 74 _(i) and76 _(j) (i, j=1-5). From the procedure described so far, the surfaceposition of the surface of wafer W is converted to Z_(k)+Z(X_(k)).

The position coordinate of wafer table WTB (wafer stage WST) iscontrolled, for example, at a time interval of 96 μsec. At each controlsampling interval, main controller 20 updates the current position ofwafer stage WST, computes thrust command values and the like to positionthe stage to a target position, and outputs the values. As previouslydescribed, the current position of wafer stage WST is computed from themeasurement results of interferometer system 118, encoder system 150(encoders 70A to 70F), and surface position measurement system 180 (Zheads 72 a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅). Accordingly, maincontroller 20 monitors the measurement results of the interferometer,the encoder, and the Z heads at a time interval (measurement samplinginterval) much shorter than the control sampling interval.

Therefore, in the embodiment, main controller 20 constantly continues toreceive the measurement values from all the Z heads (not always two)that face the scanning area of the scales (the area where probe beamsfrom the Z heads are scanned), while wafer stage WST is within theeffective stroke range. And, main controller 20 performs the switchingoperation (a linkage operation between a plurality of Z head) of the Zheads described above in synchronization with position control of waferstage WST which is performed at each control sampling interval. In suchan arrangement, an electrically high-speed switching operation of the Zheads will not be required, which also means that costly hardware torealize such a high-speed switching operation does not necessarily haveto be arranged.

FIG. 25 conceptually shows the timing of position control of wafer stageWST, the uptake of the measurement values of the Z head, and theswitching of the Z head in the embodiment. Reference code CSCK in FIG.25 indicates the generation timing of a sampling clock (a control clock)of the position control of wafer stage WST, and reference code MSCKindicates a generation timing of a sampling clock (a measurement clock)of the measurement of the Z head (and interferometer and encoder).Further, reference code CH typically shows the linkage process in theswitching of the Z head.

Main controller 20 executes the switching procedure of the Z heads bydividing the operation into two stages; the restoration and theswitching process (and the linkage process) of the Z heads. Whendescribing the switching according to an example shown in FIG. 25, firstof all, the Z heads which are operating at the time of the first controlclock are to be of a first combination, ZsL and ZsR. Main controller 20monitors the measurement value of these Z heads, and computes theposition coordinate (Z, θy) of wafer stage WST. Next, main controller 20obtains all of the Z heads on the scanning area of the Y scale and inits vicinity from the position coordinate of wafer stage WST, specifiesZ head ZsR′ which needs restoration from the Z heads, and restores theencoder at the time of the second control clock. In this case, Z headZsR′ which has been restored is in the waiting state (scale servo state)previously described, and is switched to the operating state (focusservo state) by main controller 20, after it has been confirmed that Zhead ZsR′ has faced the scanning area of the Y scale. At this point oftime, the operating Z heads become three, which are, ZsL, ZsR and ZsR′.And, from the operating Z heads, main controller 20 specifies the Z headwhose measurement values are to be monitored to compute the positioncoordinate of wafer stage WST at the time of the next control clock,according to the position coordinate of wafer stage WST. Assume that asecond combination. ZsL and ZsR′ are specified here. Main controller 20confirms whether this specified combination matches the combination thatwas used to compute the position coordinate of wafer stage WST at thetime of the previous control clock. In this example, Z head ZsR in thefirst combination and Z head ZsR′ in the second combination aredifferent. Therefore, main controller 20 executes a linkage process CHto the second combination at the time of the third control clock.Hereinafter, main controller 20 monitors the measurement values of thesecond combination ZsL and ZsR′, and computes the position coordinate(Z, θy) of wafer stage WST. As a matter of course, the switching processand linkage process CH are not performed if there is no change in thecombination. Z head ZsR which is removed from the monitoring subject, isswitched to a waiting state at the time of the fourth control clock whenZ head ZsR moves off from the scanning area on the Y scale.

Incidentally, so far, in order to describe the principle of theswitching method of the Z heads to be used in position control of waferstage WST in the embodiment, four Z heads ZsL, ZsL′, ZsR, and ZsR′ weretaken up, however, ZsL and ZsL′ representatively show any of Z heads 74_(i) (i=1 to 5), 72 a, and 72 b, and ZsR and ZsR′ representatively showany of Z heads 76 _(j) (j=1 to 5), 72 c, and 72 d. Accordingly, similarto the switching between Z heads 74 (i=1 to 5) and 76_(j) (j=1 to 5),the switching and linkage process described above can be applied to theswitching between Z heads 72 a to 72 d, and the switching between Zheads 72 a to 72 d and Z heads 74 _(i) (i=1 to 5) and 76 _(j) (j=1 to5).

By at least a part of the measurement beam being intercepted (this makesdetection of a foreign material possible, therefore, in the descriptionbelow, it will also be expressed as detecting a foreign material) by aforeign material adhered on the scale surface and the like, abnormalitymay occur in the measurement results of the encoder (X heads and Yheads) and the Z heads. In this case, the measurement beam of theencoder has an expanse of, for example, 2 mm in the measurementdirection and 50 μm in the grid line direction on the scale surface. Theprobe beam of the Z head is condensed to several μm on the diffractiongrating surface serving as a reflection surface, however, on the scalesurface, the probe beam widens to an extent of sub millimeters accordingto the numerical aperture at the scale surface (the cover glasssurface). Accordingly, even a small foreign material can be detected.Furthermore, in a practical point of view, it is extremely difficult tocompletely prevent foreign materials from entering the device and fromadhering on the scale surface for over a long period. Further, asituation can be considered where the encoder or the Z head fails towork properly, and the encoder output is cut off. Therefore, whenabnormality occurs in the measurement results of the encoder and/or theZ head, a backup operation such as to switch the measurement from themeasurement by the encoder and/or the Z head in which abnormality hasoccurred to a measurement by interferometer system 118, or to correctthe measurement results of the encoder and/or the Z head in whichabnormality has occurred using the measurement results of interferometersystem 118 becomes necessary.

In the case of exposure apparatus 100 in the embodiment, water dropletsmay remain on the scale surface. For example, the liquid immersion areafrequently passes over scale 39X₁ of wafer stage WST which is adjacentto measurement stage MST when wafer stage WST and measurement stage MSTform a scrum. Further, as for the other scales as well, at the time ofedge shot exposure, the liquid immersion area enters a part of an areaon the scale. Accordingly, the water droplets that cannot be recoveredand are left on the scale may be a source which generates abnormality inthe measurement results of the encoder and/or the Z head. In this case,when the encoder and/or the Z head detect water droplets, the beam isblocked by the water droplets which reduces the beam intensity, andfurthermore, the output signals are cut off (however, the output of themeasurement section of the Z head is different from the output of focussensor FS, and is not cut off due to the presence of water droplets).Further, because materials of a different refractive index are detected,linearity of the measurement results with respect to the displacement ofwafer stage WST (wafer table WTB) deteriorates. The reliability of themeasurement results should be inspected, on the basis of such variousinfluences.

The abnormality of the measurement results of the encoder or the Z headcan be determined from sudden temporal change of the measurementresults, or from deviation or the like of the measurement results fromthe measurement results of a different sensor system. First of all, inthe former case, when the position coordinates of wafer stage WSTobtained at every measurement sampling interval using the encoders orthe Z heads change so much from the position coordinates obtained at thetime of the previous sampling that it cannot be possible when takinginto consideration the actual drive speed of the stage, main controller20 decides that abnormality has occurred. In the latter case, theindividual measurement values of the encoders or the Z heads arepredicted from the current position of wafer stage WST, and when thedeviation of the predicted measurement values from the actualmeasurement values exceeds a permissible level which is decided inadvance, main controller 20 decides that abnormality has occurred.Further, in the embodiment, position measurement using interferometersystem 118 is performed in the whole stroke area, independently from theposition measurement of wafer stage WST using the encoder or the Z head.Therefore, main controller 20 decides that abnormality has occurred inthe case the deviation of the position coordinates of wafer stage WSTobtained using the measurement results of the encoder or the Z head fromthe position coordinates of wafer stage WST obtained using themeasurement results of interferometer system 118 exceeds a permissiblelevel which is decided in advance.

By the Z head detecting, for example, a foreign material adhered on thescale surface, abnormal measurement results can be output. However, insuch a case, by the movement of wafer stage WST, the output of the Zhead promptly returns to the normal output. Next, a response to such atemporary abnormality output will be described.

First of all, main controller 20 predicts the measurement value of the Zhead, that is, the surface position of the corresponding Y scale(measurement surface), from theoretical formulas (9) and (10) using thecurrent position (Z, θx, θy) of wafer stage WST. By obtaining thedifference between the predicted measurement value and the actualmeasurement value of the Z head, and furthermore, taking the average (orto be more precise, a movement average covering a predetermined numberof control clocks) regarding a predetermined time, main controller 20obtains offset θz. This offset θz is set to all the Z heads, and is usedas an index to inspect the measurement results of the individual Zheads.

Now, a case will be considered where a Z head ZS detects a foreignmaterial DW, which is adhered on a moving measurement target surface S₀,as shown in FIGS. 26A to 26H. First of all, as shown in FIG. 26A, Z headZS is to be in an operating state, or more specifically, in a focusservo state where the surface position of measurement target surface S₀is followed. As previously described, the reflected light of probe beamLB is received by tetrameric light receiving element ZD whichconstitutes focus sensor FS. In the operating state, as shown in FIG.26B, sensor main section. ZH including focus sensor FS follows thesurface position of measurement target surface S₀ so that the sectionalshape of the reflected light of probe beam LB is in the form of a circleon the detection surface of tetrameric light receiving element ZD, ormore specifically, so that focus error I of focus sensor FS expressed informula (7) becomes zero (I=0). At this point in time, measurementsection ZE outputs reading value E₀ corresponding to the surfaceposition of measurement target surface S₀ as a measured value of Z headZS.

Next, measurement target surface S₀ moves in the −Y direction from theposition shown in FIG. 26A, and assume that Z head ZS detects foreignmaterial DW adhering on the surface, as shown in FIG. 26C. In this case,for the sake of simply, assume that probe beam LB is completelyreflected on the surface of foreign material DW, and the principal rayof the reflected light matches the principal ray of probe beam LB. Atthis point, sensor main section ZH follows the actual reflectionsurface, or more specifically, follows surface S of foreign material DWso as to reproduce output I=0 of focus sensor FS, or more specifically,so that the sectional shape of the reflected light on detection surfaceZD is in the form of a circle, as shown in FIG. 26D. Accordingly,measurement section ZE of Z head ZS outputs reading value Ecorresponding to the surface position of surface S of foreign materialDW as the measured value of Z head ZS.

Measured value E of Z head ZS at this point diverges greatly from thepredicted measurement value of Z head ZS corresponding to the predictedsurface position of measurement target surface S₀, or more specifically,from E₀. Therefore, offset Oz also becomes a large value. So, maincontroller 20 sets a threshold value for offset Oz, and when offset Ozexceeds the threshold value, main controller 20 decides that abnormalityhas occurred in the measurement results of Z head ZS and switches Z headZS from the operating state (focus servo state) to the waiting state(scale servo state). Main controller 20 then stops updating offset Oz,after switching to the waiting state.

In the waiting state, sensor main section ZH is driven by the drivesection (not shown) so that the focal point of probe beam LB follows thepredicted surface position of measurement target surface S₀, or morespecifically, so that measurement section ZE outputs reading value E₀corresponding to the predicted surface position of measurement targetsurface S₀. At this point, the focal point of probe beam LB matches thepredicted surface position of measurement target surface S₀, and notsurface S of foreign material DW which is the actual reflection surface.Therefore, the cross section of the reflected light on detection surfaceZD becomes a non-circular shape, as shown in FIG. 26F. At this point,focus error I as expressed in formula (7) of the focus sensor FS is nolonger zero, (I≠0).

After switching to the waiting state, output I (formula (7)) of focussensor FS is monitored. In the waiting state, because the focal point ofprobe beam LB deviates from the actual reflection surface (surface S offoreign material DW) as described above, the output becomes I≠0. In thiscase, if the focal point of probe beam LB returns to the actualreflection surface, or if the actual reflection surface is displaced andthe surface position matches with the focal point of probe beam LB,output I also returns to zero. Accordingly, if output I returns to zeroin the waiting state where the focal point of probe beam LB follows thepredicted surface position of measurement target surface S0, thisindicates that the surface position of the actual reflection surface hasmatched with the predicted surface position of measurement targetsurface S₀. Accordingly, it can be decided that the influence due todetecting foreign material DW has been resolved.

Therefore, when it has been confirmed that the cross section of thereflected light on detection surface ZD has returned to a circular shapeas shown in FIG. 26H and output I of focus sensor FS has returned tozero or to approximately zero, main controller 20 switches Z head ZSfrom the waiting state (scale servo state) to the operating state (focusservo state) as shown in FIG. 26G. Main controller 20 then begins toupdate offset Oz again, after performing the switching to the operatingstate.

Incidentally, surface position information of measurement target surfaceS₀ cannot be taken out from Z head ZS in the waiting state. Therefore,main controller 20 predicts the measurement value of Z head ZS in thewaiting state from the measurement results of interferometer system 118,and by substituting the predicted value, computes the position (Z, θy)of wafer stage WST.

By the handling so that the individual Z heads in which the abnormalitydescribed above is generated are made to wait, it becomes possible toperform drive control of wafer stage WST without switching all the Zheads (surface position measurement system 180) to a different sensorsystem. Incidentally, the threshold value with respect to offset Ozdescribed above should be appropriately changed depending on the stateof exposure apparatus 100, such as, for example, at the time of startup, reset, and exposure. Further, as in the method which will bedescribed below, the entire Z heads (surface position measurement system180) can be switched to another sensor system.

When abnormality is detected in the measuring instrument system, such asthe output signal of Z heads 72 a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to 76₅ (refer to FIG. 6) of surface position measurement system 180 being cutoff, main controller 20 immediately performs a backup operation so as toswitch to a position (Z, θy) servo control of wafer stage WST byinterferometer system 118 (refer to FIG. 6) in order to prevent theservo control of the position (Z, θy) of wafer stage WST (wafer tableWTB) from stopping. More specifically, main controller 20 switches themeasuring instrument system used to compute the position coordinates ofwafer stage WST (wafer table WTB) from surface position measurementsystem 180 (Z heads 72 a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅) tointerferometer system 118. On this operation, a linkage process isperformed so that the position coordinates of wafer stage WST that havebeen computed are successive.

FIG. 27 is a view showing an outline of a linkage process in a switching(and a reversed switching) from servo control of the position (Z, θy) ofwafer stage WST by surface position measurement system 180 to servocontrol of the position (Z, θy) of wafer stage WST by interferometersystem 118.

First of all, main controller 20 performs pre-processing for linkageprocess with respect to each control clock (CSCK). In this case, at thetime of the first measurement clock (MSCK) and the like shown in FIG. 27indicated by a solid black figure, the output signals of both thesurface position measurement system 180 and interferometer system 118are constantly monitored. However, in actual practice, the measurementclock of interferometer system 118 occurs more frequently than themeasurement clock of surface position measurement system 180, however,in this case, in order to avoid complication, only the measurement clockwhich occurs simultaneously is shown. At the time of control clockgeneration, main controller 20 computes the position coordinate (Z, θy)of wafer stage WST from the measurement result of Z heads (ZsL, ZsR)(hereinafter described as surface position measurement system (ZsL,ZSR)) of surface position measurement system 180 as in FIG. 27 at thetime of the first control clock generation, and also computes theposition coordinate (Z′, θy′) of wafer stage WST from the measurementresults of the interferometer system (IntZ) corresponding to the Zinterferometer of interferometer system 118. Then, main controller 20obtains the difference of the two position coordinates (Z, θy) and (Z′,θy′), and takes a moving average MA_(K) (Z, θy)−(Z′, θy′) for apredetermined clock number K, and keeps it as a coordinate offset O.However, in FIG. 27, the calculation of the differential moving averageis indicated by reference code MA.

As previously described, this coordinate offset O can be used also as anindex to determine the abnormality generation in the measurement resultsof the surface position measurement system (ZsL, ZsR). If an absolutevalue of coordinate offset O is equal to or under a permissible valuedecided beforehand, main controller 20 will decide that no abnormalityhas occurred, and if the absolute value exceeds the permissible value,then main controller 20 will decide that abnormality has occurred. Atthe time of the first control clock in FIG. 27, main controller 20decides that no abnormality has occurred, therefore, uses the positioncoordinate (Z, θy) of wafer stage WST computed from the measurementresults of the surface position measurement system (ZsL, ZsR) as theposition coordinate used for the servo control of wafer stage WST.

On detecting the abnormality of the output signals of the surfaceposition measurement system (ZsL, ZsR), main controller 20 promptlyperforms the linkage process to the interferometer system. In this case,assume that at the time of the 1₃ clock in FIG. 27, abnormality occursin the output signals of the Z head system (ZsL, ZsR), such as forexample, the output signals being cut off. In FIG. 27, the state wherethe output signals are cutoff is shown by an outlined figure.Incidentally, because scale servo previously described is possible withthe Z heads of the embodiment, the output signals actually are rarelycut off, however, in this case, to simplify the description, a case isillustrated where the output signals are cut off.

Then, main controller 20 adds the coordinate offset O kept in the firstcontrol clock just before to the position coordinate (Z′, θy′) of waferstage WST computed from the measurement results of the interferometersystem at the time of the second control clock, so that the positioncoordinate coincides with the position coordinate (Z, θy) of wafer stageWST computed from the measurement results of the surface positionmeasurement system (ZsL, ZsR) at the time of control clock (in thiscase, at the time of the first control clock) just before. Then, untilthe recovery of the output signals is detected, main controller 20performs the servo control of the position (Z, θy) of wafer stage WST,using the position coordinate {(Z′, θy′)+O} to which this offsetcancellation has been performed.

Incidentally, in FIG. 27, the output signals of two Z heads ZsL and ZsRwere cut off at the time of the 1₃ clock. As well as the two outputsignals, even in the case when one of the output signals is cut off,when the output signals supplied becomes one or less, the positioncoordinate of wafer stage WST cannot be computed using the theoreticalformulas (11) and (12), therefore, main controller 20 performs a similarswitching of the servo control of the position (Z, θy) of stage WST.

And, on detecting the recovery of the output signals of the surfaceposition measurement system (ZsL, ZsR), main controller 20 promptlyperforms a reverse linkage process from interferometer system 118 to thesurface position measurement system (ZsL, ZsR). In this case, assumethat the output signals of Z heads ZsL and ZsR are restored at the timeof the 2₃ clock in FIG. 27. At the time of the third control clock afterhaving detected the recovery, main controller 20 substitutes theposition coordinate {(Z′, θy′)+O} supplied from the interferometersystem to which offset cancellation has been applied into theoreticalformulas (9) and (10) and computes the measurement values that each ofthe Z heads ZsL and ZsR are to show, and performs initialization.However, in FIG. 27, this process is shown by reference code CH. Fromthe next fourth control clock onward, similar to the time of the firstclock, main controller 20 performs the usual servo control by thesurface position measurement system (ZsL, ZsR) At the same time, maincontroller 20 begins to update coordinate offset O again.

As a matter of course, not only in the case when the output signals fromthe Z heads are cut off as described above, main controller 20 performsa similar switching of the servo control of the position (Z, θy) ofwafer stage WST also in the case when the reliability of the outputsignals is low. In this case, main controller 20 secures the reliabilityof the output signals by using coordinate offset O previously describedas an index. At the time of the fifth control clock in FIG. 27, maincontroller 20 judges that the reliability has become less than apermissible level, and the position coordinate (Z′, θy′) of wafer stageWST computed from the measurement results of the interferometer systemis used as the position coordinate used for servo control. Incidentally,because coordinate offset O at this point of time is also unreliable,correction is to be performed using the latest coordinate offset O outof the coordinate offsets O which have been verified in the past. And,in the case when the reliability is sufficiently restored, the positioncoordinate (Z, θy) of wafer stage WST computed from the measurementresults of the surface position measurement system (ZsL, ZsR) is used asthe position coordinate used in servo control, similar to the time ofthe first and fourth clocks.

When abnormality occurs in surface position measurement system 180, maincontroller 20 selects a suitable processing method according to thegeneration timing. As a processing method that can be performedfrequently, the following three methods are prepared. First of all, (a)an alert of abnormality generation is issued to a user, however, thecontrol is switched to a servo control of the position of wafer stageWST by interferometer system 118 by automatic operation withoutinterrupting the processing. (b) An alert is issued to a user, and theuser is requested to make a judgment such as, whether to continue theprocess believing that the backup operation has functioned normally, toswitch from the servo control of the position of wafer stage WST byinterferometer system 118 to the servo control according to surfaceposition measurement system 180 (Z heads 72 a to 72 d, 74 ₁ to 74 ₅, and76 ₁ to 76 ₅), to perform the focus calibration and the focus mappingall over again, or to cancel the process. (c) Perform automaticswitching of the servo control of the position of wafer stage WST,without issuing an alert. Method (a) should be applied at the time ofexposure, whereas method (b) should be applied at the time of focuscalibration and focus mapping. Incidentally, method (c) is to be appliedat the time of switching of the servo control of the position of waferstage WST from the control by surface position measurement system 180 (Zheads 72 a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅) described later onto the control by interferometer system 118.

Because the influence of the air fluctuation on the Z heads is extremelysmall when compared with the interferometer, by using surface positionmeasurement system 180 (Z heads 72 a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to76 ₅) (refer to FIG. 6), drive control of wafer stage WST can beperformed with high precision. However, the Z head measures the surfaceposition by scanning a probe beam on a surface (reflection surface) ofthe scale. Therefore, when water droplets, dust, flaws and the likeadhere on the scale surface as previously described and the foreignmaterials are scanned, an inconvenience occurs such as an abnormalsignal being output by a Z head or the output signals from the Z headbeing cut off. Accordingly, when abnormality occurs in the outputsignals from surface position measurement system 180, a means to preventabnormal operation in the servo control of the position (Z, θy) of waferstage WST becomes necessary.

As one of the means, there is a method of switching to a wafer tablecontrol using another sensor system, as in the backup control byinterferometer system 118 (refer to FIG. 6) previously described.However, in order to inspect the reliability of the output signals ofsurface position measurement system 180 (Z heads 72 a to 72 d, 74 ₁ to74 ₅, and 76 ₁ to 76 ₅), the output signals must be monitored to someextent. By reason of the position control of wafer stage WST, outputsignals are to be monitored when the control sampling clock (controlclock) is generated a predetermined number of times. Therefore, a delaytime occurs from the time when abnormality actually occurs in Z heads 72a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅ until main controller 20(refer to FIG. 6) detects the abnormality.

As an example of abnormality generation, a time interval will beconsidered herein in which a probe beam of a Z head scans a foreignmaterial adhering on the surface of a scale, and the Z head outputs anabnormal measurement result. Assume that a probe beam of a Z head scansa foreign material while wafer stage WST is moving at a speed of 1m/sec. In this case, the foreign material is to be a water dropletsufficiently larger than the expanse of the probe beam of the Z head.Further, for the sake of simply, the probe beam (scanning beam) of the Zhead is to be completely blocked by the water droplet. However, at thispoint, the scale servo of the Z head is not to be performed. When theexpanse of the probe beam is 1 mm, the time required for the probe beamto be completely cut off by the foreign material is 1 msec. Morespecifically, the output signal of focus sensor FS of the Z head takes 1msec to be completely cut off, and moves into an unmeasurable state.Accordingly, the Z head (measuring section ZE) also takes 1 msec tooutput abnormal measurement results.

Meanwhile, in the case when, for example, the control clock numbermonitoring the output signal is 5, since the generation interval of thecontrol clock is about 100 μsec in the embodiment, the time required formain controller 20 to actually detects abnormality from the abnormalitygeneration in the output signal of the Z head (delay time) turns out tobe 0.5 msec. This delay time 0.5 msec is not so negligibly short whencompared with disappearance time 1 msec of the output signal at the timeof abnormality generation obtained above. Accordingly, on detecting theabnormality of the output signals of Z heads 72 a to 72 d, 74 ₁ to 74 ₅,and 76 ₁ to 76 ₅, it is difficult to switch to a servo control of theposition (Z, θy) of wafer stage WST using another sensor system withoutthe precision declining, especially in the case when wafer stage WST isdriven at a high speed.

From the consideration described above, as an alternate means, it isdesirable to use a stable sensor system whose temporal change of theoutput signals is moderate at the time of abnormality generation, orwhose temporal change of the output signals does not cause a notableabnormal operation. In this regard, it is favorable to useinterferometer system 118, however, as previously described, theinterferometer is greatly influenced by air fluctuation and is inferiorto surface position measurement system 180 in the viewpoint of precisionin servo control of the position of wafer stage WST. Therefore, a servocontrol of the position (Z, θy) of wafer stage WST by a hybrid system isfavorable that uses both interferometer system 118 serving as a mainsensor system for a stable servo control of the position (Z, θy) ofwafer stage WST, and surface position measurement system 180 (Z heads 72a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅) serving as a sub-sensorsystem to cover the precision of the servo control of the position (Z,θy) of wafer stage WST. For such a reason, in the embodiment, thefollowing two alternative methods are employed.

A First Alternative Method

In a first alternative method, main controller 20 computes a positioncoordinate of wafer stage WST to be used for servo control of position(Z, θy) of wafer stage WST from the sum of position coordinate (Z′, θy′)of wafer stage WST computed from output signals of interferometer system118 and coordinate offset O=MA_(K){(Z, θy)−(Z′, θy′)}. However, (Z, θy)denotes the position coordinate of wafer stage WST computed from theoutput signals of surface position measurement system 180, and MA_(K)denotes a moving average of a predetermined clock number K.

In the first alternative method, main controller 20 uses coordinateoffset O as in the backup operation previously described byinterferometer system 118, and inspects the reliability of the outputsignals of surface position measurement system 180 (Z heads 72 a to 72d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅). When main controller 20 confirmsthat the output signals are normal, main controller 20 takes the sum ofcoordinate offset O which has been inspected and the position coordinate(Z′, θy′) of wafer stage WST computed from the output signals ofinterferometer system 118, and performs servo control of wafer stage WSTusing the position coordinates which can be obtained from the sum.Incidentally, in the case when moving average is not applied tocoordinate offset O, when (Z′, θy′) obtained at the same time t and Oare used, this would simply mean that the position coordinate (Z, θy) ofwafer stage WST computed from the output signals of surface positionmeasurement system 180 at time t is used.

Meanwhile, in the case main controller 20 detects abnormality in theoutput signals, main controller 20 does not use coordinate offset O inwhich abnormality has been detected, and performs servo control of theposition of wafer stage WST using the position coordinate obtained fromthe sum of coordinate offset O which has been confirmed to be normal inthe preceding inspection and position coordinate (Z′, θy′) of waferstage WST computed from the output signals of interferometer system 118,or using position coordinate (Z′, θy′) of wafer stage WST computed fromthe output signals of interferometer system 118.

FIG. 28 shows an outline of a servo control of the position of waferstage WST by the hybrid system using interferometer system 118 andsurface position measurement system 180 (Z heads 72 a to 72 d, 74 ₁ to74 ₅, and 76 ₁ to 76 ₅) in the first alternative method. Incidentally,the notation in the drawing is similar to FIG. 27 previously described.As it can be seen when comparing FIG. 27 and FIG. 28, the procedure suchas the linkage process at the time of abnormality generation iscompletely the same as the backup operation by the interferometer systempreviously described except for the point that the position coordinateused for servo control of the position of wafer stage WST normally isreplaced from position coordinate (Z, θy) obtained from measurementresults of the surface position measurement system (ZsL, ZsR) to the sumof position coordinate (Z′, θy′) obtained from measurement results ofinterferometer system (Intl) and coordinate offset O. Accordingly, adetailed description of FIG. 28 will be omitted.

In the first alternative method, at the time of stable operation whenthere is no sudden change in the output signals, the sum of positioncoordinate (Z′, θy′) of wafer stage WST computed from the output signalsof interferometer system 118 and coordinate offset O becomesapproximately equal to position coordinate (Z, θy) of wafer stage WSTcomputed from the output signals of surface position measurement system180. Accordingly, at the time of stable operation, a highly preciseservo control of the position of wafer stage WST which is almost thesame level as the servo control of the position of wafer stage WST basedon the output signals of surface position measurement system 180 becomespossible.

If this first alternative method is employed, for example, in the servocontrol of the position of wafer stage WST during scanning exposure,error components by air fluctuation and the like included in themeasurement values can be corrected using the measurement values of Zheads 74 _(i) and 76 _(j) of the highly precise surface positionmeasurement system 180 at least in the Z-axis direction and the θydirection, while performing position control of wafer stage WST in theZ, θy, and θx directions based on the measurement values ofinterferometer system 118. This makes focus leveling control with highprecision at the time of scanning exposure possible.

Incidentally, in the first alternative method, the update of coordinateoffset O may be late, in order to inspect the output signals of surfaceposition measurement system 180 (Z heads 72 a to 72 d, 74 ₁ to 74 ₅, and76 ₁ to 76 ₅). Further, because moving average is applied to coordinateoffset O, the influence of the air fluctuation component ofinterferometer system 118 generated in a shorter time scale than theaverage time (the product of average number of times and control clocktime interval) cannot be sufficiently corrected, which may be ageneration factor of a control error. Incidentally, it is desirable toset the time (control clock number) required for inspection of theoutput signals long enough to perform a safe inspection, as well asshort enough to be able to sufficiently correct the influence of the airfluctuation component of a short time scale.

A Second Alternative Method

In a second alternative method, main controller 20 uses positioncoordinate (Z′, θy′) of wafer stage WST computed from output signalsinterferometer system 118 as the position coordinate of wafer stage WSTused for servo control of the position (Z, θy) of wafer stage WST. Inthis case, the influence of the air fluctuation of interferometer system118 gives a limit to the position control precision of wafer stage WST.Therefore, by using surface position measurement system 180 together,the following process is executed for higher precision in the positioncontrol of wafer stage WST.

(a) Process at the time of focus mapping: A case will be considered whenposition control of wafer stage WST in the Z, θy, and θx directions atthe time of focus mapping previously described is performed, based onmeasurement values of interferometer system 118. In this case, maincontroller 20 detects position information of wafer stage WSTindependent from the position control of wafer stage WST in the Z and Bydirections using Z heads 72 a to 72 d of surface position measurementsystem 180 during the focus mapping, at a predetermined sampling timingin synchronization with interferometer system 118. In this case, theinformation obtained at the time of focus mapping is not used untilexposure has been started. Therefore, until the beginning of exposure,main controller 20 corrects position coordinate (Z′, θ′) of wafer stageWST obtained from the detection information of interferometer system 180taken in at each sampling timing, using position coordinate (Z, θy) ofwafer stage WST obtained from the detection information of Z heads 72 ato 72 d which was taken in simultaneously. Further, at this point, maincontroller 20 inspects the reliability previously described of detectioninformation of Z heads 72 a to 72 d, and does not use the detectedposition coordinate data in which abnormality has been detected for thecorrection described above. By performing drive control of wafer stageWST in the Z and By directions based on the position coordinate of waferstage WST which has been corrected and the corresponding surfaceposition detection data of wafer W obtained in the manner describedabove, as a consequence, a highly precise focus leveling control ofwafer W becomes possible on exposure.

(b) Process in the latter half of focus calibration: A case will beconsidered when position control of wafer stage WST in the Z-axisdirection is performed based on measurement values of interferometersystem 118 (Z interferometers 43A and 43B), at the time of a Z scanmeasurement using aerial image measurement device 45 in the process inthe latter half of the focus calibration previously described. In theaerial image measurement where the image of the object is picked upduring a constant speed scan (during the Z scan), the positioncoordinate of wafer stage WST at the time when the control samplingclock is generated a predetermined number of times is used to correct aspeed shift from a predetermined speed of wafer stage WST during themeasurement. The correction of the speed shift herein means that acalculation that takes into consideration the speed shift (morespecifically, the shift of the sampling position) is performed, at astage to obtain the best focus position from the imaging data.Accordingly, in this case, the correction should be performed, byobtaining the speed shift using the positional information of waferstage WST obtained from the output signals of Z heads 74 _(i) and 76_(j) (i and j are one of 1 to 5) of surface position measurement system180.

(c) Process at the Time of the Exposure

In exposure apparatus 100 of the embodiment, sufficient precision in theoverlay and the image formation of the transfer pattern is secured by asynchronized drive control in which reticle stage RST is driven andcontrolled following up the movement of wafer stage WST. In thissynchronized drive system, even if a control error of wafer stage WSToccurs, if the follow-up performance of reticle stage RST issufficiently good, the error will not affect the precision in theoverlay and the image formation of the transfer pattern. Therefore,reticle stage RST is to be configured drivable in the Z-axis directionand the θy direction, and a position coordinate of wafer stage WSTobtained from output signals of surface position measurement system 180(Z heads 72 a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅) is to be used asa position target value for follow-up control of reticle stage RST inthe Z-axis direction and the θy direction.

FIG. 29 is a block diagram typically showing a configuration of thesynchronized drive control system of reticle stage RST and wafer stageWST which uses both the interferometer system and the surface positionmeasurement system. In FIG. 29, a target value calculation outputsection 120 outputs a position target value of wafer stage WST to waferstage drive system 124. Wafer stage drive system 124 drives wafer stageWST according to a difference between the position target value and themeasured value from interferometer system 118. The measured value frominterferometer system 118 is converted into a measured value of surfaceposition measurement system 180 (Z heads 72 a to 72 d, 74 to 74 ₅, and76 ₁ to 76 ₅) by an interferometer/Z head output converter 121, and isfurthermore magnified by a projection magnification of 1/β² times, andthen is output to reticle stage drive system 11 as a position targetvalue of reticle stage RST. Reticle stage drive system 11 drives reticlestage RST according to a difference between the position target valueand the measured value from reticle interferometer 116. Incidentally, inthe control system of the stage (table), the stage itself does notconfigure a component of the control system, and further a signal ofsome sort is not supplied to the interferometer system from the stage,however, in FIG. 29, the configuration shown in the drawing is employedfor the sake of simplicity. In FIG. 29, in the section surrounded by aphantom line (two-dot chain line), when wafer stage WST moves,interferometer system 118 measures the positional information of waferstage WST, and at the same time, surface position measurement system 180also measures the positional information of wafer stage WST, and theposition (displacement) of wafer stage WST obtained based on the outputof surface position measurement system 180 is multiplied by 1/β² times,and is input to the reticle stage control system as a target value. Thisphysical phenomenon is rearranged and shown in FIG. 29, tointerferometer/Z head output converter 121 converting the output ofinterferometer system 118 which measures the position of wafer stage WSTto the output of the Z heads (surface position measurement system).

In the control system shown in FIG. 29, even if an error occurs in theservo control of wafer stage WST by interferometer system 118, becausehighly precise measured values from surface position measurement system180 (Z heads 72 a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅) are inputinto reticle stage drive system 11 as position target values,synchronized drive control can be performed with sufficient precision.Incidentally, in this second alternative method, a control error mayoccur due to the air fluctuation component of interferometer system 118generated in a short time scale, as in the first alternative method.

In the second alternative method described above, because servo controlof the position of wafer stage WST is performed using interferometersystem 118, it is favorable in terms of stability. On the other hand, interms of control accuracy, while it is inferior to the servo control ofthe position of wafer stage WST using surface position measurementsystem 180, unless the air fluctuation component generated in a shorttime scale does not occur, or if it is sufficiently small, it should notbe a problem in particular. Incidentally, it is desirable to set thetime (control clock number) required for inspection of the outputsignals long enough to perform a safe inspection, as well as shortenough to, be able to sufficiently correct the influence of the airfluctuation component of a short time scale.

Incidentally, main controller 20 can perform control of wafer stage WSTby a method (referred to as a third alternative method for the sake ofconvenience) which uses the first alternative method and the secondalternative method together. In this third alternative method, becausethe accuracy of the position control of wafer stage WST of the firstalternative method is constantly secured, positional shift at the timeof the AF mapping and speed shift at the time of the Z-direction scanmeasurement in the latter processing of the focus calibration can besuppressed. In addition to this, because the correction process of thecontrol error according to the second alternative method is also added,the control error at the time of AF mapping and the Z-direction scanmeasurement can be effectively reduced.

Incidentally, so far, in order to simplify the description, while maincontroller 20 performed the control of each part of the exposureapparatus including the control of the stage system (such as reticlestage RST and wafer stage WST), interferometer system 118, encodersystem 150, surface position measurement system 180 and the like, as amatter of course, at least a part of the control of main controller 20described above can be performed shared by a plurality of controllers.For example, a stage controller which performs operations such as thecontrol of the stage system, switching of the heads of encoder system150 and surface position measurement system 180 can be arranged tooperate under main controller 20. Further, the control that maincontroller 20 performs does not necessarily have to be realized byhardware, and main controller 20 can realize the control by softwareaccording to a computer program that sets each operation of somecontrollers that perform the control sharing as previously described.

As described in detail above, according to exposure apparatus 100 of theembodiment, main controller 20 drives wafer stage WST in at least one ofa direction orthogonal to the XY plane (the Z-axis direction) and a tiltdirection (the θy direction) with respect to the XY plane based onpositional information detected by interferometer system 118, whileadjusting the positional information of wafer stage WST measured byinterferometer system 118 (Z interferometers 43A and 43B) using thepositional information detected by surface position measurement system180. By this arrangement, it becomes possible to drive wafer stage WSTin at least one of the Z-axis direction and the θy direction with goodaccuracy (refer to the first alternative method previously described),based on positional information detected by interferometer system 118 (Zinterferometers 43A and 43B) whose error components have been corrected,while correcting the error components of the positional informationdetected by interferometer system 118 (Z interferometers 43A and 43B)caused by air fluctuation of measurement beams using the positionalinformation detected by surface position measurement system 180 whoseshort-term stability of measurement is superior (highly precisemeasurement can be performed) when compared with interferometer system118.

Further, according to exposure apparatus 100 of the embodiment, bytransferring and forming the pattern of reticle R in each shot area onwafer W mounted on wafer table WTB which is driven with good precisionas described above, it becomes possible to form a pattern with goodprecision in each shot area on wafer W.

Further, according to exposure apparatus 100 of the embodiment, maincontroller 20 drives wafer stage WST in the Z-axis direction and thetilt direction with respect to the XY plane based on informationdetected by interferometer system 118 which is superior in long-termstability of measurement, and by using information detected by surfaceposition measurement system 180 which is superior (a highly precisemeasurement is possible) in short-term stability of measurement whencompared with interferometer system 118, performs various calibrationprocesses previously described (refer to the second alternative methodpreviously described) to improve alignment accuracy of a pattern andwafer W in the Z-axis direction and the tilt direction with respect tothe XY plane (at least in the θy direction). As a consequence, itbecomes possible to form a pattern on wafer W held by wafer table WTBwith high precision for over a long period of time.

Further, according to exposure apparatus 100 of the embodiment, byperforming the focus leveling control of the wafer with high accuracyduring scanning exposure using the Z heads without measuring the surfaceposition information of the wafer W surface during exposure, based onthe results of focus mapping performed beforehand, it becomes possibleto form a pattern on wafer W with good precision. Furthermore, in theembodiment, because a high-resolution exposure can be realized by liquidimmersion exposure, a fine pattern can be transferred with goodprecision on wafer W also from this viewpoint.

Incidentally, in the embodiment above, when focus sensor FS of each Zhead performs the focus-servo previously described, the focal point maybe on the cover glass surface protecting the diffraction grating surfaceformed on Y scales 39Y₁ and 39Y₂, however, it is desirable for the focalpoint to be on a surface further away than the cover glass surface, suchas, on the diffraction grating surface. With this arrangement, in thecase foreign material (dust) such as particles is on the cover glasssurface and the cover glass surface becomes a surface which is defocusedby the thickness of the cover glass, the influence of the foreignmaterial is less likely to affect the Z heads.

In the embodiment above, the surface position measurement system whichis configured having a plurality of Z heads arranged exterior to wafertable WTB (the upper part) in the operating range (a range where thedevice moves in the actual sequence in the movement range) of waferstage WST and detects the Z position of wafer table WTB (Y scales 39Y₁and 39Y₂) surface with each Z head was employed, however, the presentinvention is not limited to this. For example, a plurality of Z headscan be placed on a movable body (for example, wafer stage WST in thecase of the embodiment above) upper surface, and a detection device,which faces the heads and has a reflection surface arranged outside themovable body that reflects the probe beam from the Z heads, can beemployed, instead of surface position detection system 180. The pointis, as long as the detection device is a device that has one or morethan one detection positions arranged in at least a part of an operatingarea of a movable body (for example, wafer stage WST in the embodimentabove), and detects positional information of the movable body in theZ-axis direction using detection information detected at each detectionposition when the movable body is positioned at any of the detectionpositions, the device can be employed instead of surface positiondetection system 180.

Further, in the embodiment above, an example has been described wherethe encoder system is employed that has a configuration where a gridsection (an X scale and a Y scale) is arranged on a wafer table (a waferstage), and X heads and Y heads facing the grid section are placedexternal to the wafer stage, however, the present invention is notlimited to this, and an encoder system which is configured having anencoder head arranged on the movable body and has a two-dimensional grid(or a linear grid section having a two-dimensional placement) facing theencoder heads placed external to the movable body can also be adopted.In this case, when Z heads are also to be placed on the movable bodyupper surface, the two-dimensional grid (or the linear grid sectionhaving a two-dimensional placement) can also be used as a reflectionsurface that reflects the probe beam from the Z heads.

Further, in the embodiment above, the case has been described where eachZ head is equipped with sensor main section ZH (the first sensor) whichhouses focus sensor FS and is driven in the Z-axis direction by thedrive section (not shown), measurement section ZE (the second sensor)which measures the displacement of the first sensor (sensor main sectionZH) in the Z-axis direction, and the like as shown in FIG. 7, however,the present invention is not limited to this. More specifically, withthe Z head (the sensor head), the first sensor itself does notnecessarily have to be movable in the Z-axis direction, as long as apart of the member configuring the first sensor (for example, the focussensor previously described) is movable, and the part of the membermoves according to the movement of the movable body in the Z-axisdirection so that the optical positional relation (for example, aconjugate relation of the light receiving elements within the firstsensor with the photodetection surface (detection surface)) of the firstsensor with the measurement object surface is maintained. In such acase, the second sensor measures the displacement in the movementdirection from a reference position of the movable member. As a matterof course, in the case a sensor head is arranged on the movable body,the movable member should be moved so that the optical positionalrelation of the measurement object of the first sensor, such as, forexample, the two-dimensional grid described above (or the linear gridsection having a two-dimensional placement) and the like with the firstsensor is maintained, according to the position change of the movablebody in a direction perpendicular to the two-dimensional plane.

Further, in the embodiment above, while the case has been describedwhere the encoder head and the Z head are separately arranged, besidessuch a case, for example, a head that has both functions of the encoderhead and the Z head can be employed, or an encoder head and a Z headthat have a part of the optical system in common can be employed, or acombined head which is integrated by arranging the encoder head and theZ head within the same housing can also be employed.

Further, in the embodiment above, while the case has been describedwhere the surface position of the measurement target surface is measuredin a first control state of the Z head, or more specifically, in a focusservo control state, in which sensor main section ZH (the first sensor)which houses focus sensor FS as shown in FIG. 7 is driven in the Z-axisdirection by the drive section (not shown) so that an optical positionalrelation with the measurement target surface is maintained, anddisplacement in the Z-axis direction of the first sensor in this stateis measured, using measurement section ZE (the second sensor), thepresent invention is not limited to this. More specifically, the surfaceposition of the measurement target surface can be measured in a secondcontrol state of the Z head, or more specifically, in the scale servocontrol state where the position of the first sensor in the Z-axisdirection is controlled according to the measurement results of thesecond sensor, using the drive section (not shown), and the outputsignals (focus error I) of the first sensor are measured in such astate. In accordance with the same principle, instead of the Z head, a Zhead with the first sensor fixed, or a sensor head configured only fromthe first sensor and does not include the drive section (not shown) andthe second sensor can be used. Further, instead of the Z head, as wellas the focus sensor by an optical pickup method, a displacement sensorhead which can measure the displacement of the subject can be used.

Incidentally, in the embodiment above, while the lower surface of nozzleunit 32 and the lower end surface of the tip optical element ofprojection optical system PL were substantially flush, as well as this,for example, the lower surface of nozzle unit 32 can be placed nearer tothe image plane (more specifically, to the wafer) of projection opticalsystem PL than the outgoing surface of the tip optical element. That is,the configuration of local liquid immersion device 8 is not limited tothe configuration described above, and the configurations can be used,which are described in, for example, EP Patent Application PublicationNo. 1 420 298, the pamphlet of International Publication No.2004/055803, the pamphlet of International Publication No. 2004/057590,the pamphlet of International Publication No. 2005/029559 (thecorresponding U.S. Patent Application Publication No. 2006/0231206), thepamphlet of International Publication No. 2004/086468 (the correspondingU.S. Patent Application Publication No. 2005/0280791), Kokai (JapaneseUnexamined Patent Application Publication) No. 2004-289126 (thecorresponding U.S. Pat. No. 6,952,253), and the like. Further, asdisclosed in the pamphlet of International Publication No. 2004/019128(the corresponding U.S. Patent Publication No. 2005/0248856), theoptical path on the object plane side of the tip optical element mayalso be filled with liquid, in addition to the optical path on the imageplane side of the tip optical element. Furthermore, a thin film that islyophilic and/or has dissolution preventing function may also be formedon the partial surface (including at least a contact surface withliquid) or the entire surface of the tip optical element. Incidentally,quartz has a high affinity for liquid, and also needs no dissolutionpreventing film, while in the case of fluorite, at least a dissolutionpreventing film is preferably formed.

Incidentally, in the embodiment above, pure water (water) was used asthe liquid, however, it is a matter of course that the present inventionis not limited to this. As the liquid, a chemically stable liquid thathas high transmittance to illumination light IL and is safe to use, suchas a fluorine-containing inert liquid can be used. As thefluorine-containing inert liquid, for example, Fluorinert (the brandname of 3M United States) can be used. The fluorine-containing inertliquid is also excellent from the point of cooling effect. Further, asthe liquid, liquid which has a refractive index higher than pure water(a refractive index is around 1.44), for example, liquid having arefractive index equal to or higher than 1.5 can be used. As this typeof liquid, for example, a predetermined liquid having C—H binding or O—Hbinding such as isopropanol having a refractive index of about 1.50,glycerol (glycerin) having a refractive index of about 1.61, apredetermined liquid (organic solvent) such as hexane, heptane ordecane, or decalin (decahydronaphthalene) having a refractive index ofabout 1.60, or the like can be cited. Alternatively, a liquid obtainedby mixing arbitrary two or more of these liquids may be used, or aliquid obtained by adding (mixing) at least one of these liquids to(with) pure water may be used. Alternatively, as the liquid, a liquidobtained by adding (mixing) base or acid such as H⁺, Cs⁺, K⁺, Cl⁻, SO₄²⁻, or PO₄ ²⁻ to (with) pure water can be used. Moreover, a liquidobtained by adding (mixing) particles of Al oxide or the like to (with)pure water can be used. These liquids can transmit ArF excimer laserlight. Further, as the liquid, liquid, which has a small absorptioncoefficient of light, is less temperature-dependent, and is stable to aprojection optical system (tip optical member) and/or a photosensitiveagent (or a protection film (top coat film), an antireflection film, orthe like) coated on the surface of a wafer, is preferable. Further, inthe case an F₂ laser is used as the light source, fomblin oil can beselected. Further, as the liquid, a liquid having a higher refractiveindex to illumination light IL than that of pure water, for example, arefractive index of around 1.6 to 1.8 may be used. As the liquid,supercritical fluid can also be used. Further, the tip optical elementof projection optical system PL may be formed by quartz (silica), orsingle-crystal materials of fluoride compound such as calcium fluoride(fluorite), barium fluoride, strontium fluoride, lithium fluoride, andsodium fluoride, or may be formed by materials having a higherrefractive index than that of quartz or fluorite (e.g. equal to orhigher than 1.6). As the materials having a refractive index equal to orhigher than 1.6, for example, sapphire, germanium dioxide, or the likedisclosed in the pamphlet of International Publication No. 2005/059617,or kalium chloride (having a refractive index of about 1.75) or the likedisclosed in the pamphlet of International Publication No. 2005/059618can be used.

Further, in the embodiment above, the recovered liquid may be reused,and in this case, a filter that removes impurities from the recoveredliquid is preferably arranged in a liquid recovery device, a recoverypipe or the like.

Incidentally, in the embodiment above, the case has been described wherethe exposure apparatus is a liquid immersion type exposure apparatus.However, the present invention is not limited to this, but can also beemployed in a dry type exposure apparatus that performs exposure ofwafer W without liquid (water).

Further, in the embodiment above, the case has been described where thepresent invention is applied to a scanning exposure apparatus by astep-and-scan method or the like. However, the present invention is notlimited to this, but may also be applied to a static exposure apparatussuch as a stepper. Further, the present invention can also be applied toa reduction projection exposure apparatus by a step-and-stitch methodthat synthesizes a shot area and a shot area, an exposure apparatus by aproximity method, a mirror projection aligner, or the like. Furthermore,the present invention can also be applied to a multi-stage type exposureapparatus equipped with a plurality of wafer stages, as is disclosed in,for example, Kokai (Japanese Unexamined Patent Application Publication)No. 10-163099 and No. 10-214783 (the corresponding U.S. Pat. No.6,590,634), Kohyo (Published Japanese Translation of InternationalPublication for Patent Application) No. 2000-505958 (the correspondingU.S. Pat. No. 5,969,441), the U.S. Pat. No. 6,208,407, and the like.

Further, the magnification of the projection optical system in theexposure apparatus of the embodiment above is not only a reductionsystem, but also may be either an equal magnifying system or amagnifying system, and projection optical system PL is not only adioptric system, but also may be either a catoptric system or acatadioptric system, and in addition, the projected image may be eitheran inverted image or an upright image. Moreover, exposure area IA towhich illumination light IL is irradiated via projection optical systemPL is an on-axis area that includes optical axis AX within the field ofprojection optical system PL. However, for example, as is disclosed inthe pamphlet of International Publication No. 2004/107011, the exposurearea may also be an off-axis area that does not include optical axis AX,similar to a so-called inline type catadioptric system, in part of whichan optical system (catoptric system or catadioptric system) that hasplural reflection surfaces and forms an intermediate image at least onceis arranged, and which has a single optical axis. Further, theillumination area and exposure area described above are to have arectangular shape. However, the shape is not limited to rectangular, andcan also be circular arc, trapezoidal, parallelogram or the like.

Incidentally, a light source of the exposure apparatus in the embodimentabove is not limited to the ArF excimer laser, but a pulse laser lightsource such as a KrF excimer laser (output wavelength: 248 nm), an F₂laser (output wavelength: 157 nm), an Ar₂ laser (output wavelength: 126nm) or a Kr₂ laser (output wavelength: 146 nm), or an extra-highpressure mercury lamp that generates an emission line such as a g-line(wavelength: 436 nm) or an i-line (wavelength: 365 nm) can also be used.Further, a harmonic wave generating device of a YAG laser or the likecan also be used. Besides the sources above, as is disclosed in, forexample, the pamphlet of International Publication No. 1999/46835 (thecorresponding U.S. Pat. No. 7,023,610), a harmonic wave, which isobtained by amplifying a single-wavelength laser beam in the infrared orvisible range emitted by a DFB semiconductor laser or fiber laser asvacuum ultraviolet light, with a fiber amplifier doped with, forexample, erbium (or both erbium and ytteribium), and by converting thewavelength into ultraviolet light using a nonlinear optical crystal, canalso be used.

Further, in the embodiment above, illumination light IL of the exposureapparatus is not limited to the light having a wavelength equal to ormore than 100 nm, and it is needless to say that the light having awavelength less than 100 nm can be used. For example, in recent years,in order to expose a pattern equal to or less than 70 nm, an EUVexposure apparatus that makes an SOP or a plasma laser as a light sourcegenerate an EUV (Extreme Ultraviolet) light in a soft X-ray range (e.g.a wavelength range from 5 to 15 nm), and uses a total reflectionreduction optical system designed under the exposure wavelength (e.g.13.5 nm) and the reflective mask has been developed. In the EUV exposureapparatus, the arrangement in which scanning exposure is performed bysynchronously scanning a mask and a wafer using a circular arcillumination can be considered, and therefore, the present invention canalso be suitably applied to such an exposure apparatus. Besides such anapparatus, the present invention can also be applied to an exposureapparatus that uses charged particle beams such as an electron beam oran ion beam. In the exposure apparatus that uses the charged particlebeam, an image-forming optical system including an electromagnetic lenswhich deflects (condenses light) a charged particle beam by magneticforce is used, however, in this case, by controlling the electromagneticlens which is at least apart of the image-forming optical system usingthe positional information related to at least one of the Z-axisdirection and the tilt direction with respect to the XY plane of themovable body such as wafer stage WST obtained from the detectioninformation of a detection device such as surface position measurementsystem 180 in the embodiment above, the image-forming position of thepattern image which is to be formed by the image-forming optical systemcan be changed.

Further, in the embodiment above, a transmissive type mask (reticle) isused, which is a transmissive substrate on which a predetermined lightshielding pattern (or a phase pattern or a light attenuation pattern) isformed. Instead of this reticle, however, as is disclosed in, forexample, U.S. Pat. No. 6,778,257, an electron mask (which is also calleda variable shaped mask, an active mask or an image generator, andincludes, for example, a DMD (Digital Micromirror Device) that is a typeof a non-emission type image display device (spatial light modulator) orthe like) on which a light-transmitting pattern, a reflection pattern,or an emission pattern is formed according to electronic data of thepattern that is to be exposed can also be used.

Further, as is disclosed in, for example, the pamphlet of InternationalPublication No. 2001/035168, the present invention can also be appliedto an exposure apparatus (lithography system) that forms line-and-spacepatterns on a wafer by forming interference fringes on the wafer.

Moreover, the present invention can also be applied to an exposureapparatus that synthesizes two reticle patterns on the wafer via aprojection optical system and almost simultaneously performs doubleexposure of one shot area on the wafer by one scanning exposure, as isdisclosed in, for example, Kohyo (Published Japanese Translation ofInternational Publication for Patent Application) No. 2004-519850 (thecorresponding U.S. Pat. No. 6,611,316).

Further, an apparatus that forms a pattern on an object is not limitedto the exposure apparatus (lithography system) described above, and forexample, the present invention can also be applied to an apparatus thatforms a pattern on an object by an ink-jet method.

Incidentally, an object on which a pattern is to be formed (an objectsubject to exposure to which an energy beam is irradiated) in theembodiment above is not limited to a wafer, but may be other objectssuch as a glass plate, a ceramic substrate, a film member, or a maskblank.

The use of the exposure apparatus is not limited only to the exposureapparatus for manufacturing semiconductor devices, but the presentinvention can also be widely applied, for example, to an exposureapparatus for transferring a liquid crystal display device pattern ontoa rectangular glass plate, and an exposure apparatus for producingorganic ELs, thin-film magnetic heads, imaging devices (such as CCDs),micromachines, DNA chips, and the like. Further, the present inventioncan be applied not only to an exposure apparatus for producingmicrodevices such as semiconductor devices, but can also be applied toan exposure apparatus that transfers a circuit pattern onto a glassplate or silicon wafer to produce a mask or reticle used in a lightexposure apparatus, an EUV exposure apparatus, an X-ray exposureapparatus, an electron-beam exposure apparatus, and the like.

Incidentally, the movable body drive system and the movable body drivemethod of the present invention can be applied not only to the exposureapparatus, but can also be applied widely to other substrate processingapparatuses (such as a laser repair apparatus, a substrate inspectionapparatus and the like), or to apparatuses equipped with a movable bodysuch as a stage that moves within a two-dimensional plane such as aposition setting apparatus for specimen or a wire bonding apparatus inother precision machines.

Incidentally, the disclosures of the various publications(descriptions), the pamphlets of the International Publications, and theU.S. Patent Application Publication descriptions and the U.S. Patentdescriptions that are cited in the embodiment above and related toexposure apparatuses and the like are each incorporated herein byreference.

Semiconductor devices are manufactured through the following steps: astep where the function/performance design of the device is performed, astep where a wafer is made using silicon materials, a lithography stepwhere the pattern formed on the reticle (mask) by the exposure apparatus(pattern formation apparatus) in the embodiment previously described istransferred onto a wafer, a development step where the wafer that hasbeen exposed is developed, an etching step where an exposed member of anarea other than the area where the resist remains is removed by etching,a resist removing step where the resist that is no longer necessary whenetching has been completed is removed, a device assembly step (includingprocesses such as a dicing process, a bonding process, and a packagingprocess), an inspection step and the like.

By using the device manufacturing method of the embodiment describedabove, because the exposure apparatus (pattern formation apparatus) inthe embodiment above and the exposure method (pattern formation method)thereof are used in the exposure step, exposure with high throughput canbe performed while maintaining the high overlay accuracy. Accordingly,the productivity of highly integrated microdevices on which finepatterns are formed can be improved.

While the above-described embodiments of the present invention are thepresently preferred embodiments thereof, those skilled in the art oflithography systems will readily recognize that numerous additions,modifications, and substitutions may be made to the above-describedembodiments without departing from the spirit and scope thereof. It isintended that all such modifications, additions, and substitutions fallwithin the scope of the present invention, which is best defined by theclaims appended below.

What is claimed is:
 1. A pattern formation method in which a pattern isformed on an object held by a movable body moving substantially along atwo-dimensional plane, the method comprising: a drive process in whichwhile positional information of the movable body in a directionorthogonal to the two-dimensional plane and a tilt direction withrespect to the two-dimensional plane is detected using (i) a firstdetection device that detects the positional information of the movablebody related to the direction orthogonal to the two-dimensional planeand the tilt direction with respect to the two-dimensional plane frommeasurement results using a measurement beam irradiated along thetwo-dimensional plane between an outside of an operating area of themovable body and the movable body and (ii) a second detection devicethat has a plurality of detection positions and detects positionalinformation of the movable body related to the direction orthogonal tothe two-dimensional plane at each detection position, the movable bodyis driven in at least one of the direction orthogonal to thetwo-dimensional plane and the tilt direction with respect to thetwo-dimensional plane based on the positional information detected bythe first detection device; and a calibration process in which apredetermined calibration processing is performed using the detectioninformation of the second detection device to improve alignmentprecision of a pattern with the object in at least one of the directionorthogonal to the two-dimensional plane and the tilt direction withrespect to the two-dimensional plane.
 2. The pattern formation methodaccording to claim 1 wherein the predetermined calibration processingincludes detecting positional information in the direction orthogonal tothe two-dimensional plane and the tilt direction with respect to thetwo-dimensional plane of the movable body using the second detectiondevice on a mapping measurement in which positional information of themovable body at a plurality of detection points on the object surface isdetected while moving the movable body in a predetermined directionparallel to the two-dimensional plane, and obtaining a positional shiftrelated to at least one of the direction orthogonal to thetwo-dimensional plane and the tilt direction with respect to thetwo-dimensional plane of the movable body on the mapping measurementusing the detection information.
 3. The pattern formation methodaccording to claim 1 wherein the predetermined calibration processingincludes obtaining and correcting a speed shift of the movable body inthe direction orthogonal to the two-dimensional plane when measuring anaerial image of a predetermined mark during a constant scan of themovable body in the direction orthogonal to the two-dimensional plane,using positional information in at least one of the direction orthogonalto the two-dimensional plane and the tilt direction with respect to thetwo-dimensional plane of the movable body obtained from the detectioninformation of the second detection device.
 4. The pattern formationmethod according to claim 1 wherein the predetermined calibrationprocessing includes changing an image-forming position of a patternimage formed via an optical system, using the positional information inat least one of the direction orthogonal to the two-dimensional planeand the tilt direction with respect to the two-dimensional plane of themovable body obtained from the detection information of the seconddetection device.
 5. The pattern formation method according to claim 4wherein at the time of formation of the pattern image via the opticalsystem, the movable body is driven in at least one of the directionorthogonal to the two-dimensional plane and the tilt direction withrespect to the two-dimensional plane, based on the positionalinformation detected by the first detection device, and thepredetermined calibration processing makes an image-forming position ofthe pattern image change by driving another movable body that holds amask on which the pattern is formed in at least one of the directionorthogonal to the two-dimensional plane and the tilt direction withrespect to the two-dimensional plane, using detection information ofboth a position measuring device that measures positional information ofthe another movable body in the direction orthogonal to thetwo-dimensional plane and the tilt direction with respect to thetwo-dimensional plane and the second detection device.
 6. The patternformation method according to claim 4 wherein an image-forming positionof the pattern image is changed by driving at least some optical membersconfiguring the optical system when forming the pattern image via theoptical system.
 7. A device manufacturing method, including: forming apattern on an object by the pattern formation method according to claim1; and developing the object on which the pattern is formed.
 8. Apattern formation apparatus in which a pattern is formed on an objectheld by a movable body moving substantially along a two-dimensionalplane, the apparatus comprising: a first detection device that detectspositional information of the movable body related to a directionorthogonal to the two-dimensional plane and a tilt direction withrespect to the two-dimensional plane from measurement results using ameasurement beam irradiated along the two-dimensional plane between anoutside of an operating area of the movable body and the movable body; asecond detection device that has a plurality of detection positions, anddetects positional information of the movable body related to thedirection orthogonal to the two-dimensional plane at each detectionposition; and a controller which drives the movable body in at least oneof the direction orthogonal to the two-dimensional plane and the tiltdirection with respect to the two-dimensional plane based on thepositional information detected by the first detection device, whiledetecting the positional information of the movable body in thedirection orthogonal to the two-dimensional plane and the tilt directionwith respect to the two-dimensional plane, using the first detectiondevice and the second detection device, and performs a predeterminedcalibration processing using the detection information of the seconddetection device to improve alignment precision of a pattern with theobject in at least one of the direction orthogonal to thetwo-dimensional plane and the tilt direction with respect to thetwo-dimensional plane.
 9. The pattern formation apparatus according toclaim 8, further comprising: a surface position detection device whichdetects positional information in the direction orthogonal to thetwo-dimensional plane of an object surface at a plurality of detectionpoints, wherein the controller, as the predetermined calibrationprocessing, detects positional information of the movable body in thedirection orthogonal to the two-dimensional plane and the tilt directionwith respect to the two-dimensional plane using the second detectiondevice on mapping measurement where positional information in thedirection orthogonal to the two-dimensional plane at the plurality ofdetection points of the object surface is detected using the surfaceposition detection device while moving the movable body in apredetermined direction parallel to the two-dimensional plane, and byusing the detection information, performs a processing of obtaining apositional shift of the movable body on the mapping measurement in atleast one of the direction orthogonal to the two-dimensional plane andthe tilt direction with respect to the two-dimensional plane.
 10. Thepattern formation apparatus according to claim 8 wherein a partincluding at least a pattern plate of an aerial image measurement devicewhich measures an aerial image of a predetermined mark is arranged inthe movable body, and as the predetermined calibration processing, thecontroller performs a processing of obtaining and correcting a speedshift of the movable body in the direction orthogonal to thetwo-dimensional plane when the aerial image of the predetermined mark ismeasured by the aerial image measurement device during a constant scanof the movable body on which the pattern plate is arranged in thedirection orthogonal to the two-dimensional plane, using positionalinformation in at least one of the direction orthogonal to thetwo-dimensional plane and the tilt direction with respect to thetwo-dimensional plane of the movable body obtained from the detectioninformation of the second detection device.